CN1179248A - Apparatus and method for generating pseudorandom quantities based upon radio channel characteristics - Google Patents

Abstract

Characteristics of the radio channel are used to establish pseudorandom sequences for use in communicating information. These characteristics are the short-term reciprocity and rapid spatial decorrelation of phase of the radio channel. Due to the reciprocal nature of these radio channel characteristics, the transceivers which are communicating via the radio channel will generally both determine the same sequence. Although the determined sequences are not always sufficiently random for use in pseudorandom functions, a randomness tester can be provided to discard those sequences which are not sufficiently random. Exemplary pseudorandom communication functions include the selection of a spreading sequence in CDMA systems and the selection of a hopping sequence in a TDMA or CDMA system.

Description

Be used for producing the equipment and the method for pseudorandom quantities based on characteristics of radio channels

Background

Applicant's invention relates to uses characteristics of radio channels so that in the equipment and the method that produce pseudorandom quantities (for example, they can be used as the sequence spreading in the communication of the communication of using code division multiplexing or code division multiple access (CDMA) system or be used as hopping sequences in time division multiple access (TDMA) or cdma system) on a plurality of transceivers.

Extensive needs to secure communication in wireless communication system are obvious.Only as two examples, the information that relates to financial transaction is often by the radio exchange, and enforcement official often must carry out voice and/or data communication by radio.In these two examples, communication is very crucial by implementing almost completely in confidence, even if potential earwig can obtain strong information signal.The user of cellular radio also wishes to maintain secrecy in their communication, and these communications can transmitted on the link between mobile phone and the base station or on the direct link between the travelling carriage.

It is the information of being communicated by letter according to the system encryption that some users agree to use in advance that a safe method is provided.Several encryption methods are described in the literature, for example, and data encryption standard (DES) and public keys (PKC).As (author is W.Diffie etc. " maintaining secrecy and authentication: cryptographic introduction (Privacy and Authentication:An Introduction to Cryptography) ", publication is at Proc.IEEE the 67th volume, in March, 1979, on the 397th to 427 page) in explained, traditional secrecy system generally is to be transformed into secret text or instruction set conversely to plain text (unencrypted information) with various ways, hardware, or computer program, a mode in these modes is known by a certain user but key that other people are maintained secrecy is selected.DES is traditional encryption system.

The popular such fact of PKC system utilization, promptly seeking big prime number is easy on calculating, but the product that decomposes two big prime numbers is difficult on calculating.There is an advantage in the PKC system to other secrecy systems that resemble DES, and promptly a PKC system uses a decruption key that is different from encryption key.Such PCK user's encryption key can come forth to be used by other users, has avoided the difficulty of safe issue key.Please referring to, for example, " a kind of method (A method of obtaining DigitalSignatures and Public-Key Cryptosystems) that obtains digital signature and public keys secrecy system " (author is R.I.Rivest etc., publication is at Commun.of the ACM, 21 volumes, in February, 1978, the 120th to 126 page); " first of public key cryptography 10 years (The First Ten Years of Public-KeyCryptography) " (author is W.Diffie, and publication is at Proc.IEEE, the 76th volume, in May, 1988,560-577 page or leaf).

To a traditional system or PKC system, maintaining secrecy of message depends on the length of key to a great extent, as (author is C.E.Shannon at " communication theory of secrecy system (Communication Theory ofSecrecy Systems) ", publication is at Bell Sys.Tech.J., 28 volumes, in October, 1949, the 656th to 715 page) described in.

Unfortunately, frequent situation is, two users (as two police officers) do not have a key in advance, and this makes that the real time communication of maintaining secrecy by the conventional cryptography system is impossible.Even a PKC system also requires the user to produce a pseudorandom quantities.And popular PKC system is not proved to be safe, and suffers from the harsh requirement of the complexity and the necessary amount of information that exchanges of calculating.When the method for new attack PKC system is put into effect, the PKC system will fall back on longer exchange vector (in fact, being bigger prime number) and more complicated calculating.As a result, traditional and PKC secrecy system are unfavorable for many signal intelligences.

Make any wireless communication system the task complexity be: the wireless channel mobility that atmospheric perturbation causes, the relatively moving of system user, from building and vehicle to the change of the reflection of wireless signal etc.These channel variation cause the mistake of the information of being communicated by letter, and many effort are spent in and overcome on these mistakes.For example, some cellular radiotelephone systems convert the analog information that will send to digital information, and digital information is transformed according to a packeting error-correcting code then.Such cellular wireless system is prescribed in TIA/EIA/IS-95-A (this is a standard in mid-term to the North America cdma communication system, is published by telecommunications industry association and Electronic Industries Association (TIA/EIA)), and the content of this standard is quoted at this, for your guidance.

In a such cdma system, each wireless channel, or wireless carrier signal has a specific frequency, corresponding to the sequence spreading of each digital bit, be used for encoding from the information bit sequence of data source (for example, the digital coding part of a speech talk).The information sequence that will be communicated by letter is expanded by information sequence and sequence spreading are merged, or is mapped as one longer sequence.As a result, one or more bits of information sequence are represented by the sequence that a N " chip " (chip) is worth.Chip sequence, i.e. extend information sequence is used to modulate the frequency of wireless carrier signal then.

For example, in a transmitter, a binary message symbol b (± 1) can be expanded by b and a sequence spreading x are multiplied each other; For example, sequence spreading x can be+1 ,-1 ,+1 ,-1, comprise four binary system chips.In essence, the process of expansion will replace each binary message symbol with the escape character of one four chip: when b=+1, be+1 ,-1 ,+1 ,-1; When b=-1, be-1 ,+1 ,-1 ,+1.Be called in the process of " directly expansion " at this, each escape character is actual to be the product of an information symbol and sequence spreading.

In the second kind of extend type that is called " non-direct expansion ", different possible information symbols is replaced by different, that not necessarily be correlated with, sequence spreading.The mapping from the information symbol to the escape character like this can be looked at as a kind of form of block encoding.In the ordinary course of things, a single M binary information symbol (i.e. the symbol that can get any value of M kind probable value) is mapped to a M symbol in the possible escape character.Under the binary system situation, symbol b=+1 can be by sequence x=+1, and-1 ,+1 ,-1 replaces, and symbol b=-1 can be by sequences y=+ 1, and+1 ,-1 ,-1 replaces.

In direct or non-direct expansion, information symbol can obtain from differential code d.For example, a binary message symbol b at time n (being represented as b (n)) can be according to following relation of plane by determining at the information symbol (being represented as b (n-1)) of time n-1 with at the difference information symbol d of time n (being represented as d (n)):

B (n)=b (n-1) d (n) promptly

D (n)=b (n) b ^*(n-1) wherein ^*The expression complex conjugate.In addition, it will be appreciated that above-described information symbol can be produced by previous chnnel coding and/or spread step.

Kuo Zhan a advantage is like this, and the information of coming from many information sources can be sent out with same radio band simultaneously, and condition is to be used to represent the sequence spreading of various information source information sequence to disturb not too serious each other.In fact, different sequence spreadings is corresponding to different communication " channel ".

(author is K.Gilhosen etc. to each different aspect of traditional C DMA communication at " about the capacity (On theCapacity of a Cellular System) of cellular system ", publication is at IEEETrans.Veh.Technol., 40 the volume, in May, 1991,303-312 page or leaf) in be described.(number of patent application is 08/291 to the others of cdma communication system at United States Patent (USP) " multiple access that is used for the use Bent sequence of mobile radio telecommunications inserts coding (Multiple Access Coding using Bent Sequences forMobile Radio Comonunications) ", 693, people such as Bottomley submitted on August 16th, 1994), following U.S. patent documents: the United States Patent (USP) the 5th of authorizing Dent, 151, No. 919; Authorize Dent etc. the 5th, 353, No. 352, and be described in the U.S. Patent application that is allowed to the 08/155th, No. 557 (submission on November 22nd, 1993).These patents and patent application are here specially quoted, for your guidance.

In order to make interchannel owing to the overlapping minimum interference of bringing on time and frequency, sequence spreading should be as much as possible at random, and (like this, CDMA Channel) be quadrature each other also, and promptly the cross-correlation of sequence spreading must be zero.If (two binary sequences are just in time different on their half bit position, then their quadratures.) on the other hand, the sequence spreading of N bit length has only N quadrature.

Can see, to the expansion that this information sequence carries out, be with common block encoding similar process by a sequence in information sequence and the one group of quadrature spread sequence is merged.In many communication systems, the information sequence that be communicated by letter is carried out the block encoding of error correction.In the quadrature block encoding, the information bit of a number N is converted into 2 ^NIn the individual N bit orthogonal code one.Decipher a such orthogonal code comprise it and all 2 ^NThe member of individual Codeword Sets is relevant.The binary system sequence number that provides the code word of maximum related value has provided desired information.For example, if each of the set of 16 bit codewords of a reception and the code word with sequence number 0-15 of 16 bit long of 16 quadratures is carried out relevant, produce maximum being correlated with on the 10th code word, information signal wherein is 4 bit-binary code words 1010 (being the integer 10 of decimal representation).A sign indicating number like this is called as [16, a 4] orthogonal block code.By all code word bits of reversing, each code word can transmit another information bit.Such coding is called the biorthogonal block encoding.

Bian Ma a key character is like this, can execute (Walsh) conversion (FWT) device by a quick Wal and is carried out effectively with relevant in all orthogonal block code words in a set.For example under the situation of [128, a 7] block code, 128 input signal samplings are transformed into one 128 Wal and execute spectrum, wherein each point in this spectrum represent input signal take a sample with code word set in a value that code word is relevant.Suitable FWT processor is described in No. the 5th, 357,454, the United States Patent (USP) of authorizing Dent, and this patent here is cited, for your guidance.

As mentioned above, typical C DMA system expands to the packeting error-correcting code word to an information sequence, then the grouping code word be that unique sign indicating number sequence combines for each user.At United States Patent (USP) the 5th, 353, in the system described in No. 352, grouping code word and a scrambling mask of further information sequence not being expanded are merged.

Another kind in CDMA (or TDMA) system is usually said frequency hopping to jamproof technology.Frequency hopping is a kind of being used for to guarantee that by changing and connecting the employed carrier frequency that relevant data symbol is modulated onto the interference cases of worst case does not continue to surpass the hop period technology of (rather than time of a lasting whole connection).This feature is generally known as the interference source diversity.Frequency hopping also provides the frequency diversity of resisting the decline of moving at a slow speed for travelling carriage.And frequency hopping can also be used to eliminate the difficult task of frequency planning (this has special importance in micro cell).This can be implemented, if all sub-districts in system use same frequencies but each sub-district has different frequency hop sequences.Such system has been called Frequency Hopping Multiple Access FHMA (FHMA) system.

In a frequency-hopping system, all available frequencies can be used in each sub-district, but on the different time by a pseudo-random hop sequence generator decision.Such generator can be configured in a number of ways, for example, select the same frequency random chance of (being called as nonopiate frequency hopping) simultaneously so that produce any two sub-districts, will never select same frequency (being called as quadrature frequency hopping) simultaneously so that guarantee specified sub-district or travelling carriage, or so that the mixing that obtains two kinds of technology before (for example, signal in orthogonal frequency hopping in same sub-district, and be nonopiate with respect to the signal of adjacent sub-district).

Sequence spreading in cdma system and the frequency hop sequences in CDMA or tdma system have desirable pseudo-random characteristics jointly, and this pseudo-random characteristics is designed to help to reduce the interference of whole system.Traditional system borrows and uses pseudo-random generator to produce the sequence of these types.These pseudorandom number generators have some shortcomings.For example, on the number of the pseudo random sequence that they can produce, they are restricted typically.And these devices need a large amount of memories to be beneficial to the generation of sequence.Use pseudorandom number generator to be as an other shortcoming of the parts of base station in wireless communication system and mobile radio station, they must use the method for the common input of a complexity to guarantee that a base station and a mobile radio station of intercoming mutually produce same pseudo random sequence so that they can, for example, correctly the expansion and despreading CDMA composite signal.

Summary

According to applicant's invention, the characteristic of wireless channel is used to set up and exchange pseudorandom quantities (they can be launched machine and receiver utilization to carry out different signal processing functions, for example, expansion, the generation of despreading and frequency hop sequences).These characteristics are short-term invertibity and fast vt space decorrelations of wireless channel phase place.In other words, to a short time interval (several milliseconds magnitude), the impulse response of a wireless channel does not comprise thermal noise, being positioned at the antenna of position B from the sky alignment that is positioned at position A, is the same with the impulse response of the channel of seeing to position A from position B.Pseudorandom quantities can be established by the calculating that is equivalent to the bounded distance decoding process, and the pseudorandom quantities that is determined can be used to handle follow-up transfer of data.

The applicant also recognized, measured amount may be always enough at random so that in resembling the such signal processing of expansion and frequency hopping, be used as the pseudorandom quantities use.For example, such sequence can be arranged, they are produced the Binary Zero and 1 that becomes to have bunchiness, and this makes them be not suitable as pseudo random sequence and uses.Like this, according to one aspect of the present invention, based on the sequence that the analysis of characteristics of radio channels is produced by further screening is enough at random for use in the different signal processing technologies to guarantee them.For example, randomness test device can be used to the sequence as being set up as described in here.

In one aspect, applicant's invention provides the method for setting up pseudo random sequence, be used for handling the related signal of connection between first transceiver and second transceiver, the step that comprises has, in first transceiver, launch a plurality of sinusoidal signals, each sinusoidal signal has preset frequency and predetermined initial phase separately; In second transceiver, detect a plurality of sinusoidal signals, and launch a plurality of sinusoidal signals in the back at interval at a preset time by the emission of first transceiver.This method further comprises, in each transceiver of first and second transceivers, determines the step of the phase place of each signal from a plurality of sinusoidal signals that another transceiver receives; Difference between the phase place of definite a pair of sinusoidal signal that is received; Each difference is quantified as a corresponding value of a plurality of phase place decision values; And the pseudo random sequence of difference conduct in follow-up signal is handled of using a plurality of quantifications.

This method may further include the step of the randomicity of sequences that check is set up before using sequence in follow-up signal is handled.Be used for here being described based on other method and system of characteristics of radio channels generation and use pseudorandom quantities.

The accompanying drawing summary

Describe applicant's invention in more detail below with reference to embodiment, this embodiment only is presented and is described in the accompanying drawings with the form of example, wherein:

Figure 1A, 1B have described an exemplary multi-layer honeycomb system;

Fig. 2 is the calcspar of an exemplary cellular mobile radiotelephone system;

Fig. 3 is a calcspar of describing a communication system;

Fig. 4 describes the calcspar of communication system that a use is used to set up the single-tone comb of key sequence;

Fig. 5 shows the phase space decision region;

Fig. 6 shows the probability density function of stochastic variable Ψ;

Fig. 7 is the calcspar of the communication system of the use aiming symbol that is used to set up key sequence;

Fig. 8 is the calcspar of exemplary randomness test device;

Fig. 9 A is a matrix that is used in a word bright time slot and frequency hopping;

Fig. 9 B is the calcspar according to exemplary hopping sequences generator of the present invention;

Figure 10 is the calcspar of the unit of an in a word bright CDMA transmitter and receiver according to exemplary embodiment of the present invention; And

Figure 11 shows the performance according to the communication system of applicant's invention.

Describe in detail

Though following description is in the category of the cellular communication system that comprises portable or mobile radiotelephone and/or personal communication network (PCN), those skilled in the art will be appreciated that applicant's invention can be used to other communications applications.System survey

Figure 1A, 1B have described an exemplary multi-layer honeycomb system.Umbrella macrocell 10 (referring to Figure 1A) by a hexagon representative is to comprise many macrocell A1-A7, the part of the covering honeycomb of B1-B7 (referring to Figure 1B).Each umbrella cell can comprise the Microcell structure on basis.The wireless coverage of the Microcell on this umbrella cell and a basis can overlapping or also can be overlapping hardly.Umbrella cell 10 comprise corresponding to the avenue zone by by the Regional Representative of circle in dotted line Microcell 20 with by by Regional Representative's the Microcell 30 of circle in dash line, and the picocell 40,50 and 60 that covers each floor of a building.

Briefly, control channel is used to set up and calls out, the position of relevant mobile radio station and parameter informing base station, and the position of relevant base station and parameter notice mobile radio station.The base station is listened to the calling that is sent by mobile radio station and is inserted request, and mobile radio station is listened to beep-page message.In case receive to call out and insert message, must which sub-district of decision be responsible for by this calling.Usually, the signal strength signal intensity of this mobile radio station that is received by sub-district nearby decides.Next step, the sub-district of appointment by (for example) mobile switching centre (MSC) order be tuned to an available voice channel, this channel is to be assigned with from the voice channel group that can be linked into designated cell.

Fig. 2 is the calcspar of the cellular mobile radiotelephone communication system used of an exemplary honeycomb with shown in Figure 1A, the 1B.This communication system comprises and macrocell separately, Microcell, the base station 110 that picocell is relevant; Mobile radio station 120 and MSC140.There are control and processing unit 130 in each base station, and it is communicated by letter with MSC, and MSC is connected to the public switched telephone network (not shown) again.Each base station also comprises a voice channel transceiver 150 and a control channel transceiver 160 at least, their Be Controlled and processing unit 130 controls.Mobile radio station 170 comprises the speech and a control channel transceiver 170 and a control and the processing unit 180 that similarly is used to control speech and control channel transceiver 170 that similarly are used for transceiver 150,160 exchange messages.The transceiver 170 of this mobile radio station can also with transceiver 170 exchange messages of another one mobile radio station.

After having provided the general introduction total to example wireless communications, (can implement according to technology of the present invention in this system) describes below an intrinsic stochasticity in the wireless channel and how to be utilized to substitute as pseudo-random sequence generator.Consider to comprise that all have the Galois of being included in territory GF (M=2 ^m) in the n-dimensional vector space of vector of element, that is, and all r=(r ₁, r ₂..., r _n), r wherein _i∈ GF (M=2 ^m).(below, vector or sequence are represented that by boldface type the scalar sum function is shown by the common aspect word table.) for a certain Hamming radius t, M ⁿIndividual vector r is the t-ball that is loaded into S ball, that is, the maximum number with non-contacting ball of radius t is S.Vector in ball is mapped to a representative that comprises that ball center.Making the set of S representative is { c ₁, c ₂..., c _s.Each representative vector c _iHave length n and can be mapped to a binary system vector k with length m n.The corresponding binary system set of vectors of order is K={k ₁, k ₂..., k _s.

If transmitter and receiver can be set up a common sequence k who is comprised among the set K with high probability _i, sequence k so _iCan be used for an information sequence from transmitted from transmitter to receiver communication is expanded, or be used to set up a frequency hop sequences that will be used in the communication period of information sequence.In addition, if an earwig can determine this common sequence k _iProbability almost be zero, safe communication also reaches-need not introduce additional encryption and decryption algorithm and realizes cryptosecurity so.

Ball according to applicant's invention is constructed under the noise in wireless channel and system hardware and other inconsistent situation, has increased transmitter and receiver and has set up such common sequence k _iProbability.Usually, transmitter is set up a sequence r _T, receiver is set up a different sequence r _RAs infructescence r _T, r _RFall in the same ball, they will be mapped to the same sequence k among the set K.

Like this, applicant's invention provides and has been used to set up two sequences (at transmitter, another is at receiver) so that two sequences fall into method and apparatus in the same ball with high probability.These sequences will be because the complicated character of time-variant wireless channel will often represent pseudo-random characteristics.Those are not pseudorandom sequences, if desired, and can detected and eliminating.And two sequences not situation seldom in same ball are detected very soon, and the process of setting up a common sequence is repeated.With one arbitrarily the ball of vector correlation determined effectively in real time with low hardware complexity.First exemplary embodiment of the present invention will be described in the category of the foundation of the key sequence of encrypting and using in encryption now.Then, the more generally usage of the sequence of setting up as pseudorandom quantities will be explored.Sequence is set up

General communication link comprises two communication channels: channel receiver from first user's transmitter to second user, channel receiver from second user's transmitter to first user.People can think that this link is included in the 3rd channel of wanting to obtain by the earwig of the information of first user and second user exchange.This simple case is shown in Fig. 3, has wherein shown the first user A, the second user B and earwig E.Usually, the characteristic of AB channel, BA channel and AE channel all changes in time.Thermal noise in each channel is by additive noise term n _i(t), i=1,2,3 representatives.

Though they change in time, the impulse response of A-B channel is the same with the impulse response (except thermal noise) of B-A channel, that is to say, on the time interval of the weak point of several milliseconds magnitudes, link is reversible.Will be appreciated that when thermal noise (with other possible imperfection) was comprised, link was not reversible.

Also have, this point is important below understanding, and promptly the impulse response of A-B channel and B-A channel is different from the impulse response of first user to earwig's A-E channel and second user to earwig's B-E channel.The appearance of these difference is because along with the phase place decorrelation apace of the variable signal of locus.

Setting up two kinds of methods of sequence is described below.The single-tone comb

Below back to back description comprise and once send two single-tones, but as described in the back, it will be appreciated that once to send plural single-tone.

With reference to figure 4, suppose that emission comprises having frequency f to first transceiver (for example by the employed transceiver of the first user A) at k signaling interval [kT, (k+1) T] ₁And f ₂, and have the signal s (t) of two sine waves of equal initial phase offset φ and ENERGY E.The arbitrary mode of the signal s (t) that is launched in can be in many ways produced, for example, by the output signal of 401,403 or frequency synthesizers of two suitable oscillators is amplified and addition, and the result is upconverted to a suitable transmission frequency by modulating a carrier signal.Neglect modulation, the signal s (t) that is launched is provided by following formula: $s\left(t\right)=\sqrt{2E/T}\cos (2\mathrm{\π}{f}_{1}t+\mathrm{\φ})+\sqrt{2E/T}\cos (2\mathrm{\π}{f}_{2}t+\mathrm{\φ})$ Formula 1

Usually, the signal s (t) that is launched is by aerial radiation, and passes such as the such passage of air, this passage borrow introduce since multipath transmisstion the time become decline and adding has double-side band power spectral density N ₀/ 2 white Gaussian noise n (t) and change the signal of emission.The effect of passage is figured by square 404.

The signal that receiver obtains from passage it carries out down-conversion and amplification (low-converter and amplifier are not shown) among Fig. 4, and resulting signal r (t) and local cos (the 2 π f that produce of receiver oneself ₁T) and cos (2 π f ₂T) relevant.As shown in Figure 4, each relevant can execution by suitable blender 405,407 and reducible integrator 409,411, (integrator carries out integration to the output signal of blender in continuous time interval T=1/2 π fi) is though known many other the devices of those skilled in the art also can be used.The output signal that is produced by correlator is low pass filtering device 413,415 filtering routinely, so that suppress (up-conversion) and signal and perhaps because the component that the wireless signal that is close to causes.

Suppose sinusoidal wave cos (2 π f ₁T) and cos (2 π f ₂T) quadrature also is separated by by the correlation bandwidth of channel at least, is provided by following formula by the signal r (t) that second transceiver (for example second user B) receives at interval k signaling: $r\left(t\right)=\sqrt{2{\mathrm{\Λ}}_1^2\left(k\right)E/T}\cos (2\mathrm{\π}{f}_{1}t+{\mathrm{\θ}}_1\left(k\right))+\sqrt{2{\mathrm{\Λ}}_2^2\left(k\right)E/T}\cos (2\mathrm{\π}{f}_{2}t+{\mathrm{\θ}}_2\left(k\right))+n\left(t\right)$ Range coefficient Λ i (k) wherein, i=1, the 2nd, independently, with the stochastic variable that distributes.

To a channel that is subjected to Rayleigh (Rayleigh) distribution decline, variable Λ i (k) has the Rayleigh probability density that is provided by following formula Formula 2

σ wherein ²=E{ Λ ² _i(k) } be a characteristic of channel, and E{.} represent with respect to p _ΛMathematic expectaion.Phase term θ ₁(k) and θ ₂(k) be mutually independent random variables, each has an equally distributed probability density on interval [π, π].

The similar expression of r (t) can be derived for the communication channel with other characteristics to received signal, for example, and Lai Si (Rice) decline that distributes.For example, the probability density of this distribution channel of Lay is provided by following formula:

Formula 3 is I wherein ₀(.) is the Bessel function of zeroth order correction, and s ²Be the power of direct sighting distance component.

In the transceiver of the second user B, filtered correlator output signal is provided to a differential phase detector 417, and this detector produces one at phase term θ at each time interval T ₁(k) and θ ₂(k) estimated value of difference between.Continuous phase place difference estimated value is provided for a quantizer 419, and it distributes the corresponding phase value in a plurality of predetermined phase values to give each phase place difference estimated value.According to applicant's invention, only require that different time phase place difference estimated value at interval is mutually incoherent.(below, the time, label k will be lost, if can not cause ambiguity.)

The base band differential signal that is produced by the differential phase detector 417 of receiver B is provided by following formula:

U _B=2 Λ ₁Λ ₂Eexp[j (θ ₁-θ ₂)]+Λ ₁N ₁+ Λ ₂N ₂ ^*Formula 4

=X _B+ jY _BN wherein ₁And N ₂Be to have zero-mean and variance is σ ²=2EN ₀The complex value Gaussian random variable, " ^*" the expression conjugation.Phase place difference estimated value is by Φ ^B=tan ^-1Y _B/ X _BProvide.Point out that as top the second user B is quantified as in M the predetermined phase values one to phase place difference estimated value, produces a quantizer output signal Q (Φ ^B).Fig. 5 has described phase place-space decision region of M=4.In this drawing, estimative phase place Φ ^B(it desirable 0 to 360 ° between any value) is quantified as four values.For example, interval [0,360] is divided into 4 zones (as shown in Figure 5), wherein

Region R ₁It is interval [0 °, 45 °] and [315 °, 360 °]

Region R ₂It is interval [45 °, 135 °]

Region R ₃It is interval [135 °, 225 °]

Region R ₄It is interval [225 °, 315 °]

If Φ ^B∈ R ₁, quantize output Q (Φ ^B)=0 °.

If Φ ^B∈ R ₂, quantize output Q (Φ ^B)=90 °.

If Φ ^B∈ R ₃, quantize output Q (Φ ^B)=180 °.

If Φ ^B∈ R ₄, quantize output Q (Φ ^B)=270 °.

These phase places can (for example) be mapped to information bit then: 0 ° → 00,90 ° → 01,180 ° → 11,270 ° → 10.

Differential phase detector or phase measurement device 417 can produce analog measurement or the digital measured value to the instantaneous phase of baseband signal.A suitable difference detector is a United States Patent (USP) the 5th of authorizing Dent, 084, No. 669 and authorize the United States Patent (USP) the 5th, 220 of Holmqvist, the combination of two phase detectors described in No. 275, these two patents are here specially quoted for your guidance.

By whenever k=1,2 ..., the estimation-quantizing process above repeating during n, the second user B are set up one and are quantized phase place difference estimated value sequence, are provided by following formula: $r_B=[Q\left({\mathrm{\Φ}}_1^B\right),Q\left({\mathrm{\Φ}}_2^B\right),...,Q\left({\mathrm{\Φ}}_n^B\right)].$ Formula 5

This is by the sequence r of the phase value of quantizer 419 generations _BBe stored in the buffer 421, the device of random access memory, shift register or equivalence for example, the length that this buffer 421 has is by each parameter decision of minimum range error correcting deocder 423.The phase place difference estimated value sequence of error correcting deocder 423 change quantizations in receiver B also produces one corresponding to receiver key sequence k _BOutput signal.Replacedly, perhaps combine what the following Fig. 8 of regarding to discussed, phase value sequence r with the generation key _BCan be transferred to a randomness test device.

In fact, the size of buffer 421 is determined by the length of the key sequence of being wanted.If decoder 423 has block length N and dimension k, the time delay of buffer is N to this example so, and wherein comb is included in send-only two single-tones of while each time in N time.Describe as following, can send plural single-tone simultaneously, thereby this has reduced the time delay of buffer.For example, if T single-tone sent simultaneously, then can quantize T-1 phase difference, the buffer time delay is N/ (T-1) at every turn.

Be buffered the vector r that device 421 produces _BN element arranged, and each is the M system, and like this, the vector of N-element is any one input of a variety of minimum distance decoder 423.A kind of useful decoder is the bounded distance decoding device, it is the decoder of a low complex degree, (author is R.Blahut at " theory and practice of error control coding (Theory and Practice of Error Control Codes) ", Addison-Wesley, Reading, MA, 1983, the 7th chapter) be described in, this joint content is here specially quoted for your guidance.Decoder 423 becomes an other N symbol, i.e. interested key sequence k to N the sign map that is produced by buffer _B, as described in greater detail.

It will be appreciated that the signal processing operations of carrying out can be carried out by a suitable Digital Signal Processing (DSP) device in numeric field in receiver.Such configuration has been arranged, almost the modulation of any kind can be by detected with the digital sampling of suitably handling received signal to the programming of DSP device, for example described at the U.S. Patent application No. 07/967/027 (" multi-mode signal processing ") of authorizing Dent etc., this file is here specially quoted for your guidance.It will be appreciated that the DSP device can be implemented with hard-wired logic, perhaps best is that as an integrated digital signal processor, for example an application-specific integrated circuit (ASIC) (ASIC) is implemented.Certainly, will be appreciated that ASIC can comprise carrying out the hard-wired logic of needed function optimum, when speed or other performance parameter were more important than the versatility of programmable digital signal processor, this was a common selected arrangement.

In a kind of mode and use and top similar hardware, the first user A sets up its quantification phase place difference estimated value sequence from the signal of second user B emission.Through the time-delay after insignificant first user emission, promptly to compare with the correlated bandwidth of channel and to want little time-delay for one, second user B emission comprises and has frequency f ₁And f ₂And the signal of two sine waves of phase deviation that equates and energy.In other words, first user A emission, second user B emission then, first user A emission then, or the like, in a kind of mode that interweaves, to keep reversible hypothesis.

Suppose that the first user A is the radio telephone that moves with 100km/ hour speed with respect to base station or other transceivers (the second user B), and use radio-frequency carrier in the 900MHz scope.If the time-delay between first user's the emission and second user's the emission is 10 microseconds, radio telephone will only mobile 0.28mm in each time-delay, and this is one and compares negligible distance with the wavelength of 0.3m.Like this, the signal from different reflector scatterings should be relevant very doughtily.In addition, the time-delay of one 10 microsecond is longer than allowing all signal rays owing to multipath transmisstion to arrive the required time of second user usually, and than guaranteeing several milliseconds of required weak points of channel invertibity.If move slower or the time-delay shorter, the invertibity of channel can be more accurate.

Like this, the first user A forms a base band differential signal that is provided by following formula (output of its differential phase detector):

U _A＝2Λ ₁Λ ₂Eexp[j(θ ₁-θ ₂)]+Λ ₁V ₁+Λ ₂V ₂ ^*

＝X _A+jY _A

Formula 6 is V wherein ₁And V ₂Be independent of N ₁And N ₂The phase difference of the estimation that is produced by the first user A is Φ ^A=tan ^-1Y _A/ X _AIt will be appreciated that, since the invertibity of channel, U _AAnd U _BUnique difference be additive Gaussian noise.

By repeating estimation-quantizing process continuously, the first user A sets up a phase place difference estimated value sequence that is provided by following formula: $r_A=[Q\left({\mathrm{\Φ}}_1^A\right),Q\left({\mathrm{\Φ}}_2^A\right),...,Q\left({\mathrm{\Φ}}_n^A\right)].$ Formula 7 these sequences are stored in first user's the buffer 421 of transceiver and are provided for corresponding error correcting deocder in first transceiver.

From these signals that is sent out, earwig E can obtain a base band differential signal that is provided by following formula

U _E=2 Λ ₃Λ ₄Eexp[j (θ ₃-θ ₄)]+Λ ₃V ₃+ Λ ₄V ₄ ^*Formula 8

=X _E+ jY _EΛ wherein _i, i=1,2,3,4 is separate.The phase difference of earwig's estimation is Φ _E=tan ^-1Y _E/ X _EIn addition, θ _i, i=1,2,3,4, be mutually independent random variables.Earwig E can set up a phase place difference estimated value sequence that is provided by following formula: $r_E=[Q\left({\mathrm{\Φ}}_1^E\right),Q\left({\mathrm{\Φ}}_2^E\right),...,Q\left({\mathrm{\Φ}}_N^E\right)]$

Formula 9

As mentioned above, three sequences that are established or vector r _A, r _BAnd r _EIn each be the input signal that is passed to corresponding error correcting deocder.The output signal that is produced by decoder is corresponding to key sequence k _A, k _B, k _EWill point out, need not carry out encryption at transmitter A, B.The number that decoder has limited possible key increases the probability that first user and second user set up same key, is introduced in more detail as following.

In order to be interpreted as any single-tone f ₁, f ₂Must have the frequency of enough separating so that their phase place reason independently, order $\mathrm{\ψ}\underset{=}{\mathrm{\Δ}}({\mathrm{\θ}}_1-{\mathrm{\θ}}_2)-({\mathrm{\θ}}_3-{\mathrm{\θ}}_4).$

Formula 10

And definition $g\left(x\right)=\frac{1-{\mathrm{\&alpha;}}^2}{4{\mathrm{\&pi;}}^2}\frac{\sqrt{1-{\mathrm{\&alpha;}}^2\mathrm{co}{s}^{2}x}+\mathrm{\&alpha;}\cos x{\cos }^{-1}(-\mathrm{\&alpha;}\cos x)}{{(1-{\mathrm{\&alpha;}}^2{\cos }^{2}x)}^{3/2}}$ Formula 11 wherein ${\mathrm{\&alpha;}}^2={\mathrm{<figure-callout\; id="0"\; label="J"\; filenames="A9619265800382.png"\; state="\{\{state\}\}">J</figure-callout>}}_0^2\left({\mathrm{\&omega;}}_D\mathrm{\&tau;}\right)/[1+{({\mathrm{\&omega;}}_1-{\mathrm{\&omega;}}_2)}^2{\mathrm{\&sigma;}}^2];$ J ₀It is zero Bessel function; ω _DBe because the Doppler frequency shift that relatively moving between transmitter and receiver causes; τ is a propagation delay time; σ is the interradial time delay expansion of multipath signal.So, as at " microwave mobile communication (Microwave Mobile Communications) " (W.C.Jakes, Jr edits, the chapter 1 that JohnWiley and Sons published in 1974) middle explanation, ψ is a stochastic variable with the probability density function that is provided by following formula: $p_{\mathrm{\&psi;}}\left(\mathrm{\&psi;}\right)=4{\mathrm{\&pi;}}^2{\&Integral;}_0^{\mathrm{\&pi;}}g\left(x\right)[g(x+\mathrm{\&psi;})+g(x-\mathrm{\&psi;})]\mathrm{<figure-callout\; id="12"\; label="dx\; Formula"\; filenames="A9619265800421.png"\; state="\{\{state\}\}">dx</figure-callout>}$ Formula 12

Fig. 6 has shown parameter α ²The probability density function p as the function of ψ/π of five kinds of different values _ψFrequency separation (ω for 40KHz ₁-ω ₂) and the time delay of 5 microseconds expansion σ (even to ω _DThe worst case of τ=0, α ²＜0.4), stochastic variable ψ distributes almost evenly.In this case, quantizer is quantized into phase place difference estimated value each phase value in M the phase value with equal probability 1/M.The phase place that the fail safe of this system depends on single-tone by communication channel by the degree of decorrelation.If decorrelation almost is completely, so, an earwig is that the workload that this system of destruction must do approaches key sequence k _A, k _BCarry out the workload of exhaustive search.

It will be appreciated that the analysis of front is simplified with the initial phase offset that equates by making two single-tones have identical energy, for example, this can be easy to obtain by phase-locked loop.Usually, only need these parameters scheduled, promptly known by two transceivers in advance, but a such system is more complicated than above-described system.

Also have, the analysis of front has only been considered at any once two single-tones of transmission, but usually, comb can comprise the plural single-tone that sends simultaneously, and the analysis of front is applicable to the right continuously of such single-tone comb.In fact, sequence r _A, r _BThe comb of single-tone that can be by sending a right quantity simultaneously and estimation and the right phase difference of each continuous single-tone of quantification and produce simultaneously.Send in the time of two or more single-tone and wishes, because the initial phase of control single-tone easily like that, cause the system of a complexity reduction.

And, the frequency separation between the single-tone in a pair of single-tone needn't equal another to frequency separation.That is to say that " comb " can have " tooth " of inhomogeneous placement.Also have, needn't consider it only is that continuous single-tone is right; That is to say that " tooth " of a centering can be separated by other " tooth ".For example, if comb comprises tactic 10 single-tone f of above raising frequency rate ₁, f ₂..., f ₁₀, the even distribution of necessity of stochastic variable ψ (seeing formula 12) can obtain by pairing, such as single-tone f ₁And f ₄f ₂And f ₅f ₃And f ₆Or the like.Only needing the single-tone of every centering is that quadrature separates, and promptly frequency separation must be enough as mentioned above.Guiding (pilot) symbol

A comb that replaces above-mentioned transmission sine wave, sequence k _A, k _BCan be only based on some aiming symbols (for example, be used for the operation of synchronous first transceiver and second transceiver and the bit that is sent out) and be established.Such synchronization bit typically is comprised in the specific synchronization field of the message of launching in the legacy cellular radio telephone system, and this knows for those skilled in the art.Two kinds of methods setting up sequence based on aiming symbol are described below.

Sequence k can be by carrying out Hard decision decoding and the sequence as a result of the aiming symbol of decoding is mapped to the center of ball and set up roughly to aiming symbol.It is believed that will be with by in the sequence of second user decoding by any mistake in the sequence of first user decoding wrong the same.Like this, two aiming symbol sequences will be mapped to same ball and produce same key.Even have not together by the sequence of first user decoding with by the mistake in the sequence of second user decoding, but two sequences also will be mapped to same ball with high probability, and produce same key.A possible shortcoming of this method is to need many aiming symbols to make the earwig be difficult to all possibilities of limit on calculating.If aiming symbol is the synchronization bit in the cellular radiotelephone system, believe so now, need 60 bits at least.

It will be appreciated that necessary aiming symbol needn't be sent together, promptly needn't use all synchronization bits in a frame of a CDMA Channel or in the time slot of a TDMA channel.For example, any one of the synchronization bit in the frame or a plurality of can being used with any one or a plurality of synchronization bit of other frame.These frames only need be separated by a time interval longer than the correlation time of above-described channel.

A kind of method of setting up the more refining of sequence based on aiming symbol is to use channel condition information rather than Hard decision decoding.In this method, first and second users carry out interpolation to known aiming symbol and the output of interpolater are quantized, and form class is similar to regard to based on single-tone combs the described mode of the method for setting up sequence.

For example, the signal that receives carried out necessary down-conversion, amplification, filtering after, second user determines a phase estimation value to each bit in the sync section of CDMA frame.Certainly, first and second users can agree to use other one group of known bit.Second user is to the difference of known bits decision between each phase estimation value and predetermined phase separately.These phase place difference estimated values are quantized and are provided for one then and set up the described minimum distance decoder of sequence or offer one below in conjunction with the described randomness test device of the generation of sequence spreading or frequency hop sequences in conjunction with combing by the transmission single-tone in the above.

Fig. 7 is a calcspar that is used to carry out the system of this use aiming symbol " method of refining ".In first transceiver, the data that be launched are encrypted according to key sequence by encryption equipment 701.Certainly, before key sequence is established, encryption equipment will transmit the data that will be launched simply and not change.Multiplexer 703 merges encrypted data that will be launched and known aiming symbol, and this aiming symbol can be the bit that is used for the synchronous and expense signaling of conventional wireless phone.Aiming symbol need only be launched with known phase place.The data that interweave that the device 703 of being re-used forms and the sequence of aiming symbol are provided for pulse shaper and upconverter 705 so that by being the communication channel transmission information of feature usually with decline and additive white Gaussian noise.

In second transceiver that receives, the signal from channel receives if required, by down-conversion, and is passed through a matched filter 707.The signal that is produced by matched filter 707 is divided into a signal and a signal that comprises the aiming symbol of reception that comprises the data that are sent out of reception by a switch 709 (or riffle sampler) of suitably controlling.Interpolater 711 measure the phase place of the aiming symbol that receives and be formed on the phase place (generally being rotated) of each measurement by channel fading and the phase place of the transmission that corresponding aiming symbol is known between difference.Interpolater 711 these phase place difference estimated values of best low-pass filtering.The phase difference value that is interpolated device 711 generations is quantized device 713 and quantizes, and is stored in buffer 715 so that add up enough phase difference values.Decoded then device 717 decodings of the sequence of phase difference value are so that produce more than one about the described key sequence of Fig. 4.

The phase difference value that is interpolated device 711 generations also is provided for the data of a demodulator 719 (for example error correcting deocder) to recover to be sent out.Demodulator 719 also receives the data that are sent out, and these data may be by a time delay device 721 that is suitable for locking phase difference and the data that are sent out.Suppose that the data that receive are encrypted according to key sequence before emission, the transmission data of the encryption that produces by demodulator 719 and be provided for the data of decipher 723 to recover to be sent out by the key sequence that decoder 717 produces.

With a kind of above-mentioned method and hardware of being similar to, transmitter is based on the key sequence of setting up it from the transmission of receiver, and this key sequence can be used to decipher the transmission from the next encryption of receiver.Ball sealing dress (packing) and associating

Suppose that k is given and ball is scheduled, one arbitrarily the sequence general considerations that is mapped to ball be the NP-difficulty, promptly the number of the computation complexity of this problem and possible ball is proportional.The application of safe transmission and expansion hereto, the number of ball are extremely big.Yet, add that a simple structure goes up (corresponding to the representative c of ball) to candidate sequence k and can reduce computation complexity to an acceptable level.

According to applicant's invention, the set of candidate sequence is limited to the sequence sets of a linear packeting error-correcting code.The radius of ball is determined that by the error correcting capability of such sign indicating number (being the number of the mistake that can correct of this yard) receiving sequence r can be mapped to candidate sequence k by suitable known decode procedure then.

As a special example, linear Bose-Chaudhuri-Hocquenghem (BCH) sign indicating number can be used as the set of candidate sequence k; The process (described in the book of writing as the R.Blahut that quotes in the above) that sign indicating number like this can borrow use Peterson-Gorenstein-Zierler process or Berlekamp-Massey process or any one to be used for cyclic code decoding is decoded with low complexity.If code parameters is that (n k), has smallest hamming distance d and has code sign alphabet GF (2 ^m), so long candidate sequence for mn can be 2 from a size ^MnSet be established.The Hamming radius t of this ball, or equivalently, the error correcting capability of this yard is provided by t≤[(d-1)/2].(ball needn't encapsulate very crowdedly).

Sequence r with reception of suitable randomness _A, r _BAnd r _EIt is the input that is passed to the error correcting deocder of carrying out the Berlekamp-Massey process.The output of these decoders is sequence k _A, k _BAnd k _EIn addition, to point out also that transmitter does not need to carry out to be encrypted.Decoder has limited the number of possibility sequence significantly, has therefore increased the possibility of the sequence unanimity between first and second users.Can point out, can not need decoder when very high signal to noise ratio (snr), high SNR although it is so will be difficult to obtain in an actual communication systems.Randomness test

Exemplary embodiment has in the past been explained how the intrinsic stochasticity of certain characteristics of radio channels can be utilized and has not been used the generation of traditional pseudorandom quantities to obtain key sequence and do not need by air interface exchange pseudorandom quantities.But the applicant has had realized that the other application to these technology, for example, comprises decision pseudo-random hop sequence and sequence spreading.

Because the randomness of communication channel, the sequence r that is stored in buffer 421 or 715 is at random.Those sequences will be desirable in a basic communication system that uses Direct swquence spread spectrum or frequency-hopped spread spectrum technology.And different users can agree to use different sequences in a plurality of user's spread spectrum communication systems.

On the other hand, in many cases, the sequence r that is stored in buffer will comprise the string of continuous Binary Zero and 1.Such sequence is not suitable as signal processing technology and uses when needing the amount of height random, for example, be not suitable for use in the sequence spreading in the cdma system, because their their cross correlation is not desirable.Therefore, the sequence that is stored in buffer 421 or 715 is provided as the input that is passed to the randomness test device, with the spectrum that guarantees sequence appropriate shape is arranged.

Fig. 8 is the calcspar of a suitable randomness test device, comprises a statistical disposition device 801 and a quality treatment device 803.The randomness of statistical disposition device 801 checking sequence r, and produce the output signal q that represents quality of randomness.Quality treatment device 803 comes down to a switch by comparator control, and whether its received signal q and corresponding sequence r and decision q value can be accepted, and promptly whether q is above a predetermined quality threshold λ, for example, and q 〉=λ whether.If like this, corresponding sequence r be used as in the direct expanding system sequence spreading or as the control signal of the frequency synthesizer in the frequency-hopping system, as will be described below.If the q value is unacceptable, if q≤λ for example, then corresponding sequence r is not used, and this sequence can be deleted from buffer.

Usually, can received q value, that is to say, be suitable for the value of the thresholding λ of quality treatment device 803, depend on the situation of channel and special application.For example a lower q value is can be received when the user learns that channel is not serious load.Consider a spread spectrum channel that now is being used to only support a connection.To second user who attempts to insert this channel, a low relatively q value can be accepted for sequence r, because the phase mutual interference expection that is caused by other connection only is quite low.In a word, under the situation of low traffic, the phase mutual interference between quite few user is an acceptable, even those users do not have to use the sequence spreading with desirable their cross correlation, allows a lower thresholding λ like this.

Statistical disposition device 801 preferably by one suitably the microprocessor of programming realize with quick enforcement for the t-check of the white property of the spectrum of sequence r with for Gauss's Kurtosis check.Check a containing element r (1), r (2), r (3) ..., the reason of the sequence r of r (N) be this sequence of decision hypothesis by one white, whether Gaussian source (desirable) generation reasonable.In addition, preferably remove any direct current biasing (being normalized to a zero-mean) in the sequence.

First step of being carried out by statistical disposition device 801 is to remove direct current biasing by the average r according to the following formula determining sequence: $\stackrel{\&OverBar;}{r}=\frac{1}{N}\underset{i=1}{\overset{N}{\mathrm{\&Sigma;}}}r\left(i\right)$ From each sequential element, deduct r then to obtain a normalized sequence r.

Then, normalized sequence is carried out related check, related check comprises from following formula decision variances sigma ²Step: and from following formula decision parameter

${\mathrm{\&sigma;}}^2=\frac{1}{N}\underset{i=1}{\overset{N}{\mathrm{\&Sigma;}}}{r}^2\left(i\right)$ $\widehat{\mathrm{\&rho;}}=\frac{\underset{i=1}{\overset{N-1}{\mathrm{\&Sigma;}}}r\left(i\right)r(i+1)}{(N-1){\mathrm{\&sigma;}}^2}$

In this, the thresholding of t-check can be selected and whether the hypothesis of ρ=0 is supported to test.If not, sequence r is excluded.T-check be in the literature know and at (for example) " statistical theory and engineering are used (Statistical Theory withEngineering Applications) " (author A.Held, Wiley Inter-Science nineteen fifty-two publishes, the 609th page) in be described, its content is here specially quoted, for your guidance.

As the 3rd step, statistical disposition device 801 is by determining parameter beta from following formula ²Carry out the Kurtosis check: ${\mathrm{\&beta;}}^2=\frac{\underset{i=1}{\overset{N}{\mathrm{\&Sigma;}}}{r}^4\left(i\right)}{{\mathrm{\&sigma;}}^4}$ The thresholding of Kurtosis check is selected in common mode, and tests with the decision parameter beta ²Whether be receptible.If the Kurtosis check has been failed, sequence r is excluded.For different N values the different thresholding that exceeds probability etc. can be set, for example at " one of normality test further develops (A Further Development of Tests for Normality) " (author E.S.Pearson, be published in the XXII volume of Biometrika, July nineteen thirty, the 239th to 249 page) described in.These different thresholdings influence the performance of cdma system in the following manner.To a big λ value, system will guarantee that good sequence produces, and many like this users can be simultaneously with limited phase mutual interference access channel.Yet for big λ value, system will introduce more time delay, because randomness test can arrive one above the many sequences of refusal before the sequence of thresholding.To slightly little λ value, can hold less user, faster but sequence is set up.

It will be appreciated that, above-mentioned t-check and Kurtosis check " on calculating is gentle ", in other words, they only need simple algorithm calculations in a small amount.As a result, these checks can be performed several candidate sequences concurrently by the microprocessor of the cheapness that provides easily.Frequency hopping

Fig. 9 A has shown time slot and the frequency hopping in example communication system.Those those skilled in the art it will be appreciated that the technology of Miao Shuing still is applicable to time slot saltus step and frequency hopping comparably separately here, rather than as compound mode described herein.In Fig. 9 A, each Traffic Channel is included in a time slot on the carrier wave of each frame.To a particular channel (being the combination of time slot and carrier frequency), time slot and carrier frequency all frame by frame change.Time slot/the carrier wave sequence that is used for a particular channel is called hopping sequences, a hopping sequences that in a given sub-district, uses can be with another hopping sequences quadrature of using in this sub-district but not with other sub-district in the hopping sequences quadrature that uses, as previously mentioned.

In Fig. 9 A, shown matrix to the time slot/carrier wave of two such tdma frames.In frame n, specific channel is included in a burst on the carrier frequency N in the time slot 6, as shown in the square of being designated as in the matrix ' X '.In next frame n+1, same channel uses another carrier frequency and time slot, and is represented as the square that is denoted as ' X ' according to the pseudorandom hopping sequences.The exemplary system that is used to determine this hopping sequences is described referring now to Fig. 9 B.

Wherein, a hop rate clock 901 provides a clock pulse to the selected timing of variation of each desirable time slot and carrier frequency.This clock pulse is used to trigger latch 903 so that the pseudo random sequence r that is stored in wherein is output.Simultaneously, one as above regards to sequence and sets up described by decision and regard to as above that Fig. 8 is described to be calculated to guarantee that it has the new pseudorandom quantities of suitable randomness to be latched to device 903.The pseudo random sequence of output is imported into mould M adder 905, and this adder can randomly be provided to the pseudorandom quantities orthogonalization from latch 903 receptions.Adder 905 is carried out the operation of mould M (frequency number in frequency memory 907).Pseudorandom quantities and quadrature biasing can also be limited to 0 to M-1 scope so that the address realm that provides in the frequency memory 907 is provided in the output of mould M adder 905.Like this, in case being provided for the correspondent frequency that 907, one of frequency memorys are stored in wherein, the address will be output, so that tuning its respective receiver in mobile radio station or base station or transmitter as selecteed frequency.Like this, the common found pseudorandom number generator of latch 903 that replaces is replaced by simpler parts.Sequence spreading

Figure 10 has illustrated one according to the exemplary transmitter 1000 and the receiver 1100 that can be used to provide CDMA transmission and reception of the present invention.In transmitter, an input data signal will be provided at chnnel coding square frame 1001, and wherein data are encoded by error correcting code.At square frame 1003, resulting symbol sebolic addressing is interleaved, and at square frame 1005, and the pseudo random sequence that signal adopts the randomness test device by Fig. 8 to provide is expanded, and this sequence is identified as the sign indicating number r of a uniqueness in Figure 10.As described above, the extended code in this exemplary embodiment is determined by the characteristic of aforesaid check wireless channel.Resulting signal is used at square frame RF carrier wave of 1007 modulation then and is launched by antenna 1009.

Receiver usually with 1100 expressions, uses the extended code despread signal of the uniqueness identical with the employed extended code that the signal that is launched is expanded in the square frame 1005 then at square frame 1101 place's restituted signals and in square frame 1103.In addition, receiver will decide unique extended code by check wireless channel in aforesaid mode.The sequence that is determined then was provided for randomness test device as shown in Figure 8 before being provided as unique extended code r like this.Except these functions, channel estimator and the speed combiner represented by square frame 1105 merge the echo of resulting signal and same signal or preceding- echo.Square frame 1003 and 1001 reverse functions respectively deinterleave 1107 and channel decoding square frame 1109 in be performed.Performance evaluation

For the performance of the consistent system of sequence that estimates the applicant, suppose that more following items are useful:

G _i＝{θ _A∈R _i，θ _B∈R _i}，B _i＝{θ _A∈R _i，θ _E∈R _i}。The probability of the symbol unanimity between first and second users is provided by following formula: $P_g=\mathrm{Pr}\left\{\underset{i=1}{\overset{M}{U}}\mathrm{Pr}\left(G_i\right)\right\}=\underset{i=1}{\overset{M}{\mathrm{\&Sigma;}}}[\mathrm{Pr}({\mathrm{\&theta;}}_A\&Element;R_i){]}^2$ The formula 13 first users probability consistent with the symbol between the earwig provided by following formula: $P_b=\mathrm{Pr}\left\{\underset{i=1}{\overset{M}{U}}\mathrm{Pr}\left(B_i\right)\right\}=\frac{1}{\mathrm{<figure-callout\; id="14"\; label="M\; Formula"\; filenames="A9619265800421.png"\; state="\{\{state\}\}">M</figure-callout>}}$ Formula 14

The probability density function of a phase theta of estimating in decision region can be derived as follows.At first, suppose Δ=θ ₁-θ ₂Given and equal zero.Equation below considering:

U＝2Λ ₁Λ ₂E+Λ ₁N ₁+Λ ₂N ₂ ^*

＝X+jY

X＝2Λ ₁Λ ₂E+Re(Λ ₁N ₁+Λ ₂N ₂ ^*)

Y=Im (Λ ₁N ₁+ Λ ₂N ₂ ^*) wherein, at Λ ₁And Λ ₂Condition under, E{X}=2 Λ ₁Λ ₂E μ; E (Y)=α variance (X)=variance $\left(Y\right)=2E{N}_0({\mathrm{\&Lambda;}}_1^2+{\mathrm{\&Lambda;}}_2^2)\underset{=}{\mathrm{\&Delta;}}{\mathrm{\&sigma;}}_0^2,$ The combination condition probability density function of X and Y is provided by following formula $P(x,y|{\mathrm{\&Lambda;}}_1,{\mathrm{\&Lambda;}}_2)=\frac{1}{2\mathrm{\&pi;}{\mathrm{\&sigma;}}_0^2}\exp \{-[{(x-\mathrm{\&mu;})}^2+y^2]/2{\mathrm{\&sigma;}}_0^2\}$ The conversion of variable is: $R=\sqrt{X^2+Y^2},$ With $\mathrm{\&theta;}={\tan }^{-1}\frac{Y}{X}$ The combination condition probability density function of θ and R is provided by following formula: $p(r,\mathrm{\&theta;}|{\mathrm{\&Lambda;}}_1,{\mathrm{\&Lambda;}}_2)=\frac{r}{2{\mathrm{\&pi;\&sigma;}}_0^2}\exp \{-(r^2+{\mathrm{\&mu;}}^2-2\mathrm{\&mu;}r\cos \mathrm{\&theta;})/2{\mathrm{\&sigma;}}_0^2\}$ In interval r ∈ [0, ∞] upper integral, can see that the probability density function of θ is given: $p_{\mathrm{\&theta;}}\left(\mathrm{\&theta;}\right|\mathrm{\&Gamma;})=\frac{1}{2\mathrm{\&pi;}}\exp (-\mathrm{\&Gamma;})$ $+\frac{1}{\sqrt{2\mathrm{\&pi;}}}\left(\sqrt{\mathrm{\&Gamma;}}\cos \mathrm{\&theta;}\right)\exp (-\mathrm{\&Gamma;}{\sin }^2\mathrm{\&theta;})[1-Q\left(\sqrt{2\mathrm{\&Gamma;}}\cos \mathrm{\&theta;}\right)]$ Wherein: $\mathrm{\&Gamma;}=\frac{{\mathrm{\&Lambda;}}_1^2{\mathrm{\&Lambda;}}_2^2}{{\mathrm{\&Lambda;}}_1^2+{\mathrm{\&Lambda;}}_2^2}\frac{E}{N_0}$

Can see Δ ' go up evenly distribution at interval [π, π].Utilization is by R _i=[π i/M, π i/M], i=1 ..., the zone that M provides, the probability of the desirable estimation phase theta in decision region is given: $\mathrm{Pr}(\mathrm{\&theta;}\&Element;R_i)=\frac{1}{2\mathrm{\&pi;}}\underset{0}{\overset{\&infin;}{\&Integral;}}\underset{-\mathrm{\&pi;}}{\overset{\mathrm{\&Gamma;}}{\&Integral;}}\underset{R_i}{\&Integral;}{p}_{\mathrm{\&theta;}}(\mathrm{\&theta;}-\mathrm{\&delta;}|\mathrm{\&Gamma;})P\left(\mathrm{\&Gamma;}\right)\mathrm{d\&theta;d\&delta;d\&Gamma;}$

Consider a use now with linear block codes of smallest hamming distance d, dimension k and block length n.Make t=[(d-1)/2] be can be decoded the number of the device mistake of correcting.The probability of the sequence unanimity of being set up by first and second users is the probability of vector in the identical decoding zone of a code word of two receptions.

Make that c is a code word with Hamming weight 1.Three vector C, r _AAnd r _BBe available.The coordinate that rearranges these vectors does not influence performance evaluation.Such arrangement is as follows:

Can prove: sequence unanimity and sequence are that the probability of c can be given: $P_l=\underset{j=0}{\overset{l}{\mathrm{\&Sigma;}}}\underset{k=0}{\overset{n-1}{\mathrm{\&Sigma;}}}\underset{{\mathrm{<figure-callout\; id="1"\; label="m"\; filenames="A9619265800421.png"\; state="\{\{state\}\}">m</figure-callout>}}_1=0}{\overset{l-j}{\mathrm{\&Sigma;}}}\underset{{\mathrm{<figure-callout\; id="2"\; label="m"\; filenames="A9619265800421.png"\; state="\{\{state\}\}">m</figure-callout>}}_2=0}{\overset{j}{\mathrm{\&Sigma;}}}\underset{{\mathrm{<figure-callout\; id="3"\; label="m"\; filenames="A9619265800421.png"\; state="\{\{state\}\}">m</figure-callout>}}_3=0}{\overset{k}{\mathrm{\&Sigma;}}}\underset{{\mathrm{<figure-callout\; id="4"\; label="m"\; filenames="A9619265800421.png"\; state="\{\{state\}\}">m</figure-callout>}}_4=0}{\overset{n-l-k}{\mathrm{\&Sigma;}}}\left[\begin{array}{c}n\\ \mathrm{\&beta;}\end{array}\right]{(1-P_g)}^{\mathrm{\&beta;}}{P}_g^{n-\mathrm{\&beta;}}$ Formula 15 is wherein:

β＝m ₁+m ₂+m ₃+m ₄

0≤j+k≤t

0≤m ₁+ j-m ₂+ k-m ₃+ m ₄≤ t like this, probability consistent with each other is given: $\mathrm{Pr}(k_A=k_B)=\underset{1}{\mathrm{\&Sigma;}}{A}_1{P}_1$ A wherein ₁Function is enumerated in the weighting that is this yard.The probability P of the sequence unanimity of setting up by the earwig _BSimilarly used p by one _bReplace p _gEquation provide.Under the condition of not using decoder, Pr (k _A=k _B)=Pr (r _A=r _B)=p ⁿ _g, and Pr (k _A=k _E)=Pr (r _A=r _E)=1/M ⁿ

It is compromise that discussion relates in the consistent system of such sequence is important.A little dimension k value produces a sign indicating number with good error correcting capability, but when k reduces, and the speed that exhaustive search can be carried out is the exponential type rising.The selection of code parameters is crucial, because sign indicating number has limited the size in candidate sequence space, but this reduces should not produce unsafe system.

To the number M of a big decision region, a bigger sign indicating number can be used, and has therefore increased the computational security of system; In addition, P _bReduce, this causes maintaining secrecy of a good probability.But this is not enough to obtain a good encryption system.Increase M, the influence of thermal noise becomes leading, needs to increase E _b/ N ₀The ratio of noise energy (bit energy with) is to reach the consistent of the sequence of maintaining secrecy with certain probability.Therefore, computational security, probability maintain secrecy and send have between the energy a kind of compromise.

As another example, consider to use (31,13) the Reed-Solomon sign indicating number on GF (32).The size (the possible code word or the number of bit sequence) of sign indicating number is 32 ¹³=2 ⁶⁵, and its computational security is in fact than DES2 ⁵⁶The computational security of (sequence using the system of digital encryption standard comprises 56 secret bits and 8 parity bits) is good.The smallest hamming distance of such Reed-Solomon sign indicating number is 18.

Figure 11 has shown a performance of using the safe communication system of such Reed-Solomon sign indicating number.Also shown the not performance of coded system of the performance of (61, a 11) Reed-Solomon sign indicating number and two.As seen from Figure 11, by the use of a channel decoder, the inconsistent probability of being set up by first and second users of key is 10 ^-8, this moment signal noise ratio E _b/ N ₀For M=64 and M=32 is respectively 11dB and 13dB.This and one do not have the communication system of decoder to compare the gain of about 9dB and 4dB are arranged respectively.And, P _r(k _A=k _E) ≈ 0, P _r(r _A=r _E) (two all is about 10 to ≈ 0 ^-41).

In such system, the use of decoder wishes that to first and second users though be not strict with as described above, the use of a decoder does not help the earwig.

Applicant's reversible sequence consistent method and equipment based on a wireless channel provide superior computational security and probability to maintain secrecy.Request for utilization person's invention, long arbitrary key sequence can be shared, and key sequence even also can be changed in communication " session ".In cellular radiotelephone system, desirable is at least whenever a mobile radio station is set up a new key sequence during to the registration of communication system, even perhaps more continually, as to each calling or whenever a preset time at interval then the time.

Replace using linear block codes, safe communication system can use the comb of 2M the quadrature single-tone that transmits by each user.Such comb system and block code system have same performance, but comb the bigger bandwidth of system requirements, and as needed by the quadrature signaling, and more complicated being used to produces the frequency synthesizer of single-tone.

In any system, the performance measurement of safety is got into probabilistic, measure different with the Shannon that maintains complete secrecy.Particularly, in the block code system, the probability that two users set up same key sequence approaches 1 and the earwig sets up the probability of same sequence is essentially 0.This is that probabilistic is maintained secrecy.Also have, the number of possible key sequence is enough big, is unpractiaca so that find correct sequence by exhaustive search.This is that computational is maintained secrecy.

In addition, the exemplary embodiment of applicant's invention is described, and wherein sequence is set up and is used to determine a pseudorandom quantities rather than a key sequence.According to these exemplary embodiments, a randomness test device can be provided to get rid of those for the not enough sequence at random of this purpose.Provide such pseudorandom quantities can be used to wherein two exemplary application, concrete is the decision of sequence spreading and the decision of hopping sequences.But those skilled in the art will see, can be used as according to the pseudorandom quantities that the present invention produced and require the part of pseudorandom quantities as any function of input.For example, need be any function of being implemented in the base station of known pseudorandom quantities or the mobile radio station for the mobile radio station that connects by wireless channel and base station therein, can be implemented according to the present invention.

Though the specific embodiment of applicant's invention is described and illustrates, should be understood that the present invention is not limited to wherein.The application has considered to belong to any and whole modifications by in the design of the applicant's of following claim qualification invention and the scope.

Claims (44)

1. method of setting up pseudo random sequence is used for communicating between first transceiver of a wireless communication system and second transceiver, and the step that comprises has:

In first transceiver, launch a plurality of sinusoidal signals, each sinusoidal signal has preset frequency and predetermined initial phase separately;

In second transceiver, detect a plurality of sinusoidal signals, and launch a plurality of sinusoidal signals in the back at interval at a preset time by the emission of first transceiver;

In each transceiver of first and second transceivers, the phase place of each signal of decision from a plurality of sinusoidal signals that another transceiver receives;

In each transceiver of first and second transceivers, the difference between the phase place of definite a pair of sinusoidal signal that is received;

In each transceiver of first and second transceivers, each difference is quantified as a corresponding value of a plurality of phase place decision values;

In each transceiver of first and second transceivers, the difference of using a plurality of quantifications is as a possible pseudo random sequence.

2. the method for claim 1 is characterized in that, further comprises step: assess the randomness of described possible pseudo random sequence and export described possible pseudo random sequence selectively as a pseudo random sequence based on described assessment.

3. the method for claim 2 is characterized in that, further comprises step: described randomness and a randomness thresholding are compared.

4. the method for claim 3 is characterized in that, wherein said comparison step further comprises based on system load selects described randomness thresholding.

5. the method for claim 2 is characterized in that, wherein the step of output comprises step selectively:

Use described pseudo random sequence as a sequence spreading in the cdma wireless communication system.

6. the method for claim 2 is characterized in that, wherein the step of output further comprises step selectively:

Use described pseudo random sequence as a hopping sequences.

7. a method of setting up pseudo random sequence is used for communicating between first transceiver and second transceiver, and the step that comprises has:

In first transceiver, emission comprises the predetermined numeric word of a plurality of bits;

In second transceiver, detect predetermined number word, and launch predetermined numeric word in the back at interval at a preset time by the emission of first transceiver;

In each transceiver of first and second transceivers, each bits of a plurality of bits the predetermined numeric word that receives from another transceiver is carried out Hard decision decoding;

In each transceiver of first and second transceivers, a plurality of bits of Hard decision decoding are mapped to a possible pseudo random sequence according to predetermined block code.

8. the method for claim 7 is characterized in that, further comprises step:

Assess the randomness of described possible pseudo random sequence and export described possible pseudo random sequence selectively as a pseudo random sequence based on described assessment.

9. the method for claim 8 is characterized in that, further comprises step: described randomness and a randomness thresholding are compared.

10. the method for claim 9 is characterized in that, wherein said comparison step further comprises based on system load selects described randomness thresholding.

11. the method for claim 8 is characterized in that, the wherein said step of output selectively comprises step:

Use described pseudo random sequence as a sequence spreading in the cdma wireless communication system.

12. the method for claim 8 is characterized in that, the wherein said step of output selectively further comprises step:

Use described pseudo random sequence as a hopping sequences.

13. a method of setting up pseudo random sequence is used for communicating between first transceiver and second transceiver, the step that comprises has:

In first transceiver, emission comprises the predetermined numeric word of a plurality of bits;

In second transceiver, detect predetermined number word, and launch predetermined numeric word in the back at interval at a preset time by the emission of first transceiver;

In each transceiver of first and second transceivers, decision is from the phase place of each bit of a plurality of bits of another transceiver reception;

In each transceiver of first and second transceivers, determine the difference between phase place that each determines and the phase place of being scheduled to accordingly;

In each transceiver of first and second transceivers, each difference is quantified as a corresponding value of a plurality of phase place decision values;

In each transceiver of first and second transceivers, the difference of a plurality of quantifications is decoded as a possible pseudo random sequence according to predetermined block code.

14. the method for claim 13 is characterized in that, further comprises step:

Assess the randomness of described possible pseudo random sequence and export described possible pseudo random sequence selectively as a pseudo random sequence based on described assessment.

15. the method for claim 14 is characterized in that, further comprises step: described randomness and a randomness thresholding are compared.

16. the method for claim 15 is characterized in that, the step of wherein said comparison further comprises based on system load selects described randomness thresholding.

17. the method for claim 14 is characterized in that, the wherein said step of output selectively comprises step:

Use described pseudo random sequence as a sequence spreading in the cdma wireless communication system.

18. the method for claim 14 is characterized in that, the wherein said step of output selectively further comprises step:

Use described pseudo random sequence as a hopping sequences.

19. an equipment that is used to set up pseudo random sequence is used for communicating between first transceiver and second transceiver, comprising:

In first transceiver, be used to launch the device of a plurality of sinusoidal signals, each sinusoidal signal has preset frequency and predetermined initial phase separately;

In second transceiver, be used to detect a plurality of sinusoidal signals, and the preset time after detecting beginning is launched the device of a plurality of sinusoidal signals by the emission of first transceiver;

In each transceiver of first and second transceivers, be used for determining the device of phase place of each signal of a plurality of sinusoidal signals of receiving from another transceiver;

In each transceiver of first and second transceivers, be used to determine the device of the difference between the phase place of a pair of sinusoidal signal that received;

In each transceiver of first and second transceivers, be used for each difference is quantified as the device of a corresponding value of a plurality of phase place decision values;

In each transceiver of first and second transceivers, be used for the difference of a plurality of quantifications being decoded as the device of a possible pseudo random sequence according to predetermined block code.

20. the equipment of claim 19 is characterized in that, further comprises:

Be used to assess the randomness of described possible pseudo random sequence and export the device of described possible pseudo random sequence selectively as a pseudo random sequence based on described assessment.

21. the equipment of claim 20 is characterized in that, further comprises:

Be used for described randomness and randomness thresholding device relatively.

22. the equipment of claim 21 is characterized in that, the wherein said device that is used for comparison further comprises based on system load selects described randomness thresholding.

23. the equipment of claim 20 is characterized in that, the wherein said device that is used for exporting selectively further comprises:

Be used for using the device of described pseudo random sequence as a sequence spreading of cdma wireless communication system.

24. the equipment of claim 20 is characterized in that, the wherein said device that is used for exporting selectively further comprises:

Be used to use the device of described pseudo random sequence as a hopping sequences.

25. an equipment that is used to set up pseudo random sequence is used for communicating between first transceiver and second transceiver, comprising:

In first transceiver, be used to launch the device of the predetermined numeric word that comprises a plurality of bits;

In second transceiver, be used to detect predetermined number word, and launch the device of predetermined numeric word in the back at interval at a preset time by the emission of first transceiver;

In each transceiver of first and second transceivers, be used for each bit of a plurality of bits of the predetermined numeric word that receives from another transceiver is carried out the device of Hard decision decoding;

In each transceiver of first and second transceivers, be used for a plurality of bits of Hard decision decoding are mapped to according to predetermined block code the device of a possible pseudo random sequence.

26. the equipment of claim 25 is characterized in that, further comprises:

Be used to assess the randomness of described possible pseudo random sequence and export the device of described possible pseudo random sequence selectively as a pseudo random sequence based on described assessment.

27. the equipment of claim 26 is characterized in that, further comprises:

Be used for described randomness and randomness thresholding device relatively.

28. the equipment of claim 27 is characterized in that, the wherein said device that is used for comparison further comprises based on system load selects described randomness thresholding.

29. the equipment of claim 26 is characterized in that, the wherein said device that is used for exporting selectively further comprises:

Be used for using the device of described pseudo random sequence as a sequence spreading of cdma wireless communication system.

30. the equipment of claim 26 is characterized in that, the wherein said device that is used for exporting selectively further comprises:

Be used to use the device of described pseudo random sequence as a hopping sequences.

31. an equipment that is used to set up pseudo random sequence is used for communicating between first transceiver and second transceiver, comprising:

In first transceiver, be used to launch the device of the predetermined numeric word that comprises a plurality of bits;

In second transceiver, be used to detect predetermined number word, and launch the device of predetermined numeric word in the back at interval at a preset time by the emission of first transceiver;

In each transceiver of first and second transceivers, be used to determine the device of phase place of each bit of a plurality of bits of receiving from another transceiver;

In each transceiver of first and second transceivers, be used for determining the device of the difference between each phase place that is determined and the corresponding phase place of being scheduled to;

In each transceiver of first and second transceivers, be used for each difference is quantified as the device of a corresponding value of a plurality of phase place decision values;

In each transceiver of first and second transceivers, be used for the difference of a plurality of quantifications being decoded as the device of a possible pseudo random sequence according to predetermined block code.

32. the equipment of claim 31 is characterized in that, further comprises:

Be used to assess the randomness of described possible pseudo random sequence and export the device of described possible pseudo random sequence selectively as a pseudo random sequence based on described assessment.

33. the equipment of claim 32 is characterized in that, further comprises:

Be used for described randomness and randomness thresholding device relatively.

34. the equipment of claim 33 is characterized in that, the wherein said device that is used for comparison further comprises based on system load selects described randomness thresholding.

35. the equipment of claim 32 is characterized in that, the wherein said device that is used for exporting selectively further comprises:

Be used for using the device of described pseudo random sequence as a sequence spreading of cdma wireless communication system.

36. the equipment of claim 32, the wherein said device that is used for selectively output further comprises:

Be used to use the device of described pseudo random sequence as a hopping sequences.

37. a wireless station comprises:

A transceiver that is used to detect the predetermined properties of wireless channel; With

One is used to use the predetermined properties of described detection to determine the processor of a pseudo random sequence.

38. the wireless station of claim 37 is characterized in that, wherein said predetermined characteristics is included in a plurality of phase difference between signals that received by described transceiver.

39. the wireless station of claim 38 is characterized in that, wherein said processor further comprises:

Be used for determining the device of a possible pseudo random sequence based on described phase difference; With

Be used to assess described possible pseudo random sequence and export the randomness test device of described possible pseudo random sequence selectively as described pseudo random sequence.

40. the wireless station of claim 39 is characterized in that, wherein said randomness test device further comprises:

Threshold compataror is used to determine whether described possible pseudo random sequence surpasses predetermined randomness thresholding.

41. the wireless station of claim 37 is characterized in that, further comprises:

The hopping sequences generator is used for selecting a frequency periodically based on described pseudo random sequence, and the frequency of described selection is used to tuning described transceiver.

42. the wireless station of claim 37 is characterized in that, further comprises:

Extended device is used for the data symbol that described transceiver uses is expanded and despreading, and described extended device uses described pseudo random sequence to decide described sequence spreading.

43. the wireless station of claim 37 is characterized in that, wherein said wireless station is a mobile radio station.

44. the wireless station of claim 37 is characterized in that, wherein said wireless station is the base station.

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