MXPA00007864A - Multiple access method and system - Google Patents

Abstract

A wireless communication system transmits data on multiple carriers simultaneously to provide frequency diversity. Carrier interference causes a narrow pulse in the time domain when the relative phases of the multiple carriers are zero. Selection of the frequency separation and phases of the carriers controls the timing of the pulses. Both time division of the pulses and frequency division of the carriers achieves multiple access. Carrier interferometry is a basis from which other communication protocols can be derived. Frequency hopping and frequency shifting of the carriers does not change the pulse envelope if the relative frequency separation and phases between the carriers are preserved. Direct sequence CDMA signals are generated in the time domain by a predetermined selection of carrier amplitudes. Each pulse can be sampled in different phase spaces at different times. This enables communication in phase spaces that are not detectable by conventional receivers. The time-dependent phase relationship of the carriers provides automatic scanning of a beam pattern transmitted by an antenna array. In waveguide communications, the carrier frequencies and phase space may be matched to the chromatic dispersion of an optical fiber to increase the capacity of the fiber.

Description

SYSTEM AND MULTIPLE ACCESS METHOD DESCRIPTION OF THE INVENTION The present invention is related to a novel multi-carrier spectrum propagation protocol for wireless and waveguide and radar communications. Multipath fading is the fluctuation in a received signal amplitude. It is caused by the interference between two or more versions of the transmitted signal that reaches the receiver at different times. This interference results from the reflections of the earth and nearby structures. The amount of multipath fading depends on the intensity and propagation time of the reflected signals and the bandwidth of the transmitted signal. The received signal may consist of a large number of waves having different amplitudes, and faces, and angles of arrival. These components combine vectorally in the receiver and cause the received signal to fade or distort. Fading and distortion change as the receiver and other objects in the radio environment move. These multi-path effects depend on the bandwidth of the signal that is being transmitted. If the transmitted signal has a narrow bandwidth, (ie, the duration of the data bits transmitted is greater than the delay that results from the multipath reflections), then the received signal exhibits deep fading as the receiver moves in a • multi-rutapa environment. This is known as 5 flat fading. A significant amount of energy control (for example, increasing the transmit power and / or gain of the receiver) is necessary to compensate for deep fading. In addition, low data rate signals experience distortion if the radio environment characteristics change • significantly during the duration of a bit of data received. Distortion is caused when the movement of the receiver or nearby object results in a Doppler frequency change of the received signal that can be compared to or be greater than the bandwidth of the transmitted signal. A broadband signal transmitted in a multi-path environment results in a selective frequency fading. The total intensity of the received signal has a relatively small variation as that the receiver moves in a multi-path environment. However, the received signal has deep fading at certain frequencies. If the duration of the data bits is smaller than the multi-path delay, the received signals experience interference from intersymbol that results from the delayed replication of the previous bits that arrived at the receiver. Frequency Division Multiple Access (FDMA) typically suffers from flat fading while multi-carrier protocols, such as Orthogonal Frequency Division Multiplexing (OFDM), suffer from selective frequency fading. CDMA typically suffers from both; however, direct sequence coding limits the effects of the multi-path for delays of less than the code chip rate. Also, the CDMA's capacity is limited by multiuser interference. Enhanced CDMA systems use interference cancellation to increase capacity; however, the applied signal processing effort is proportional to at least the cube of the bandwidth. In addition, the CDMA is susceptible to close-by-late interference, and its pseudo-noise (PN) codes require long acquisition times. For these reasons, OFDM has joined with CDMA. OFDM has a high spectrum efficiency (the overlap spectrum of subpowers) and combats selective frequency fading. However, the amplitude of each carrier is affected by Rayligh's law, which causes a flat fading. Therefore, a good channel evaluation with an appropriate detection algorithm and channel coding is essential to compensate fading. The diversity performance of the OFDM frequency can be compared to the performance of a multi-path diversity of the optimal CDMA system (which requires a Rake receiver)• because diversity is inherent in OFDM, it is much simpler to achieve than in an optimal CDMA system. An OFDM system benefits from a paralelo type of lower signal processing speed. A Rake receiver is an optimal CDMA system that uses fast serial signal processing, which results in a higher power consumption.

In addition, the OFDM technique simplifies the problem of • channel evaluation, thus simplifying the design of the receiver. In the CDMA multi-carrier, a propagation frequency is converted from serial to parallel. Each chip in The sequence modulates a different carrier frequency, in this way, the resulting signal has a structure of PN-encoded in the frequency domain, and the processing gain is equal to the number of carriers. In the multitone CDMA, the available spectrum is divided into a number of frequency bands with equivalent amplitudes that are used to transmit a direct sequence waveform of narrow bands. The frequency hopping spread spectrum can handle near-light interference well. The oldest The benefit is that it can avoid portions of the spectrum. This allows the system to better avoid interference and selective frequency fading. The disadvantages include the requirements for frequency synthesizers • complex and error correction. 5 Time jumps have a much higher bandwidth efficiency compared to the frequency jump and direct sequence. Its implementation is relatively simple. However, it has a very long acquisition time and requires error correction. 10 Each communication protocol presents different • advantages and disadvantages. The benefits can be increased by linking different protocols, but only to a limited degree. There is a need for a protocol that solves all or most of the problems, especially those associated with fading. The main object of the present invention is to provide a protocol that achieves the combined benefits of the aforementioned protocols. Another object is ^ present a spectrum propagation protocol that is specifically designed for mobile communications. These objects are achieved by multiple carrier interferometry. The protocol enabled by the present invention is Multiple Carrier Interference Access (CIMA). In CIMA the frequency and phase of each carrier that is selected so that the overlap of the weeks results in a pulse (constructive interference resulting from a zero phase relationship between the carriers) occurring in a specific time interval. The resulting signal has side lobes whose amplitudes are well below the amplitude of the pulse. In this way, orthogonality is achieved in the time domain. Because there are carriers within the time interval where an overlap produces an insignificant signal level, it can be concluded that the pulse exists in a different phase space. This phase space is defined as the time (phase) out of place between the carriers. The displacement allows the pulse to be observed in a specific time interval. A receiver tuned to multiple phase spaces can generate multiple samples of a CIMA signal. In this way, CIMA allows signals to be processed simultaneously as well as low and high data rate signals. This mitigates the multipath problems inherent in both kinds of signals and allows the system to operate at substantially reduced energy levels. Further, if the CIMA bearers are modulated by pulse amplitude, so that the overlap does not result in a pulse in a zero phase space, then the CIMA signals are visible only to the CIMA receivers tuned to a non-zero phase space. Conventional radio receivers can not detect these signals. In a medium of dispersion, as such an optical fiber, the phase space of a CIMA transmission can be selected to match the chromatic dispersion along a predefined length of the medium. The effect of dispersion is that the phases of the carriers are aligned resulting in a pulse that occurs in the middle at a predefined position. - The pending nature of the CIMA phase space time also allows for automatic tracking of a directional antenna beam pattern. If each element of an antenna array transmits a CIMA carrier, the directional antenna beam pattern scans with a period that depends on the frequency separation of the carriers and the separation between the elements of the antenna. CIMA can be used to create any of the previously mentioned protocols. It is an object of the present invention to provide methods and apparatus for transmitting and receiving CIMA signals. Up to this point, the following objects are achieved: An object of the invention is to reduce the effects of multipath interference and fading. A consequence of this object is the reduction in the required transmission energy. Another objected is to provide secure communications by creating transmissions that are difficult to intercept because they are almost impossible to detect. The low power requirements of the carriers and the transmission of the bearers in the non-zero phase spaces achieve this. Another object of the invention is to reduce the interference in other systems and to minimize the susceptibility of the communication system to all types of radio interference. Another object of the invention is to minimize and compensate for the co-channel interference that occurs when the communications system serves multiple users. Another object is to provide a spectrum propagation communication protocol that is not only compatible with adaptive digital antennas, but also allows substantial advances in antenna-order technology. Another object is to allow a spectrum propagation communication system to have the benefits of the performance of a system of limited resources, the capacity and benefits of degradation of a limited interference system, and the ability to provide the benefits of both systems. simultaneously. Other objects and benefits of the invention will be apparent in the Description of the Preferred Modalities.

BRIEF DESCRIPTION OF THE DRAWINGS Figure 1 is a schematic view of a transmitter that generates CIMA signals. Figure 2 is a second mode of the transmitter that generates CIMA signals. Figure 3 is a schematic view of a transmitter that generates CIMA beams emitted by a directional antenna. Figure 4 is a diagram of a plurality of CIMA carriers and an overlay of the carriers. Figure 5A is a diagram of eight CIMA carriers sng the relative phases between the carriers as a time function * and illustrates the phase spaces represented by the relative phases. Figure 5B is a time domain diagram of an overlay of the carrier signals s in Figure 5A. Figure 6 is a polar time diagram of an overlay of the carriers s in Figure 5A. Figure 7 is a flow diagram for a receiver that receives a CIMA signal and samples the signal in multiple phase spaces. Figure 8 s part of a frequency profile for a group of CIMA carriers. Figures 9A to 91 sa beam pattern produced by the transmitter in Figure 3 at different times. Figure 10 is a frequency-change feedback cavity that includes a path wave cavity and a frequency change device through which optical signals are circulated. Figure 11 s different CIMA signals as they propagate through an optical fiber where the phase shifts of the carriers coincide with the chromatic dispersion properties of the fiber. Figure 12A is a diagram of the frequency profile versus relative amplitude of the CIMA carriers that generate a CDMA chip sequence of direct sequence in the time domain. Figure 12B is a time domain representation of a direct sequence CDMA signal generated by the CIMA carriers s in Figure 12A. Figure 1 s a flow chart of a CIMA transmitter that converts a baseband information signal for a single user k to a CIMA signal for transmission. The data received from an input data source 12 modulates an N number of CIMA carriers, which have different carrier frequencies. This modulation occurs in a plurality of carrier mixers 14n. In this case, the frequencies of the CIMA signals are incrementally separated by a frequency of change fs. ver, the non-uniform separation of frequencies can also be used to achieve specific benefits described in US Patent Application No. 09 / 022,950, which is incorporated herein by reference. Carrier frequencies are typically chosen to be orthogonal to each other: Te jcos (fi> J + t) 8Sfjt + j) dt - 0 where Tc is the duration of the chip,? - and? -, are the carrier frequencies? th and j th, and fx and fD are arbitrary phases. A signal in the frequency band j th does not cause interference in the frequency band? Th. ver, the orthogonality of the waveforms is not required if the transmitted signals are limited by the source. The phase of each CIMA signal is established with respect to a predetermined receiver time interval and the phase space in which the CIMA signals are constructively combined when they have been received by a CIMA receiver. An incremental phase shift of e1 - is applied to each CIMA carrier by a plurality N of user delay-interval systems 16n. Each CIMA carrier has its gain adjusted by an amplitude control system 18n. The amplitude control 18n provides a gain profile in the CIMA signals. This profile can include a window of tapered amplitude with respect to the frequency domain, compensation for flat fading of the CIMA carriers in the communication channel, and pulse amplitude modulation of the CIMA carriers (which limit the existence of carriers to temporary regions near a predetermined receiver time interval for each carrier). The CIMA signals adjusted by gain are summed by a combination system 20. A frequency converter 22 can be used to convert the CIMA signals to the appropriate transmission frequencies, which are transferred to an output coupler 24. The output coupler 24 is any device that couples the CIMA transmission signals to a communication channel from which the CIMA signals are received by a receiver. For radio communications the output coupler 24 may include one or more antenna elements (not shown). For optical communications, the output coupler 24 may be to include a lens or a simple coupling element that couples light into an optical fiber. Although this diagram illustrates the generation of CIMA transmission signals as step-by-step procedures, a preferred embodiment for achieving these processes is to use digital signal processing techniques, such as Discreet Fourier Transforms.

The order of some of these processes can be changed. For example, the modulation of each CIMA carrier by the input data may be the final step of the • combination. Figure 2 illustrates a flow chart for generating CIMA signals. Each of these processes is similar to the processes shown in Figure 1. The difference between the diagrams is that in Figure 2 the CIMA signals are not combined until they are transmitted, in the communication channel. An illustration of this is shown in the Figure 3. • Figure 3 shows a data stream from the data source 12 that is being used to modulate a plurality of CIMA carriers in a plurality of mixers 25n. A CIMA carrier with a frequency Specific, a phase relationship and a gain profile is accessed in each 25n mixer. Each bit of the data source 12 modulates all the CIMA carriers. Each mixer 25n is connected to a plurality of directional antenna elements 24n; in this way, each antenna element 24n transmits only one CIMA carrier. Although the collection of CIMA bearers has data redundancy because the same bit is being modulated in multiple bearers, the frequency and phase relationships between bearers cause orthogonality in time (illustrated by the Inverse Fourier Transform of the CIMA carriers in the frequency domain). This orthogonality negates the typical decrease in bandwidth efficiency caused by data redundancy and retains the benefits of frequency diversity. The orthogonality • results from constructive and destructive interference between the 5 CIMA carriers. Constructive interference causes narrow time domain pulses with a repetition rate proportional to the inverse of the frequency spacing of carriers Fs. Figure 4 illustrates how the phase fronts of the CIMA carriers are aligned at a specific time. At other times, carriers combine destructively resulting in • levels of non-detectable signals. A composite signal 130 results from the sum of the carriers. The composite signal 130 shows a pulse envelope occurring in a predetermined time interval 135. In the case where there is no amplitude taper (ie, a rectangular window) and the CIMA carriers are uniformly separated in frequency, a composite CIMA signal is: which has a magnitude of: The CIMA signals are periodic with a period of 1 / fs for the odd numbers of N carriers and with a period 2 / fs for the even numbers of the N carriers. The main lobe has a duration of 2 / Nfs and the lateral lobes N -2 each one has a duration of 1 / Nfs. The amplitude of the lateral lobe Ia1 with respect to the amplitude of the main lobe is: 1 A (! H Nsm (p (l + l / 2) / N) Because the period ^ and the amplitude of the pulse envelope depends on the amplitude, phase and frequency separation of the CIMA carriers, the frequency of each carrier can be changed without affecting the pulse envelope while remaining in the amplitude, phase and frequency separation. In this way, the frequency hopping and the frequency change of the carriers does not affect the temporal characteristics of the composite signal 130. By providing a tapered amplitude distribution to the CIMA carriers, the amplitude of the main lobe is widened and the amplitude of the side lobes is reduced. Figure 5A illustrates the phase space of the carriers shown in Figure 4. As time moves forward, the phase relationship between the CIMA carriers changes. The straight line 113 indicates a zero phase relationship between the carriers. The sum of the carriers is seen in a specific phase space. A pulse occurs when there is a zero-phase relationship between all the carriers, even so, carriers can exert in other time domains even if there is no visible pulse. When the pulse moves in this phase space (which makes it as a periodic function of time), the pulse becomes visible. Phase zero is the phase separation in which all conventional receivers operate. This phase space is illustrated by the sum of carrier amplitudes together with any straight line that rotates around a fixed point 112. The sum of the amplitude of the probes along the line 113 as it rotates is shown in Figure 5B and in a polar diagram illustrated in Figure 6. In Figure 5A, a curved line 111 illustrates one of the many phase spaces in which a pulse can be observed. This phase space 111 occurs within a time interval that is limited by lines 115 and 117. In this time interval, the amplitude of composite signal 130 (shown in Figure 5B) is negligible. However, a receiver can selectively tune to a specific phase space by delaying each of the received carriers by a predetermined amount before adding the carriers. In this way, the receiver can detect a pulse that is otherwise invisible in the zero phase. Figure 7 shows a single user phase space receiver that is capable of obtaining samples in multiple phase spaces. A received CIMA signal is detected from the communication channel by a receiver element 52 and converted by a mixer 54 prior to • separated into its component carriers N by a frequency filter 56. Depending on how the transmission signal could have been altered by the communication channel, one of a plurality of gain compensators (not shown) can apply a gain compensation of each component n. Each component of J 10 gain compensation is divided into a number M of delay components, each of which is delayed by a compensator 60 mn of phase space delay. The result of each numbered delay component m is added in combination step 62 to reconstruct observed pulses 15 in other phase spaces. Each pulse may be delayed by a 64 m delay to synchronize the pulses before being summed into a decision step 66 which results in an estimate of the original transmission signal. In practice, the 64 m delay step can be integrated in step 66 of decision. This receiver obtains multiple samples of the pulse because it tracks the pulse through different phase spaces. In this way, the receiver benefits from the relatively slow data rate (ie, pulse period) of the CIMA carriers that combine to create the pulses. This remedies the multi-path problem of intersymbol interference. The short duration of each • Pulse allows the receiver to avoid the fading and distortion problems inherent in the system that slowly receives variable signals and the flat fading associated with the narrow band signals. Although the pulse is composed of many CIMA narrow-band carriers, flat fading (which causes deep non-Mtk fading) is avoided because the CIMA pulse depends on the interference pattern among a large number of CIMA carriers. In addition, if the number and separation between the CIMA carriers is appropriately chosen, it is unlikely that more than one CIMA carrier is located in a deep fading.

In this way, frequency diversity is achieved. Each user k may share the communication source through a single selection of the phase shift (ie, out of the tuning place) while using the same bearers as other users. If they are shared orthogonal carriers N for each user k, then N users can use the sources without a co-channel interference. In this case, there is a unique combination of phase space with respect to time for each user k. Likewise, users using different CIMA carriers can use the same phase space with respect to time without co-channel interference. Because the characteristics of the pulse depend on the frequency phase relationships between the CIMA carriers, the frequency and phase of each CIMA signal can be changed without altering the characteristics of the pulse envelope while those relations between the carriers remain unchanged. This allows a transmitter to have a frequency hop to avoid interference or improve security. The separation fs between the CIMA carriers for each user can be selected as shown in Figure 8 so that it exceeds the coherent bandwidth (i.e., the inverse of the duration of the multi-path). This results in a non-selective frequency fading on each carrier. If the adjacent CIMA bearers overlap in frequency by 50%, the capacity of the system increases twice as much as the standard limits imposed by the carriers without overlaps. Said system does not have independent channel fading characteristics on each carrier. However, CIMA carriers do not need to be adjacent in frequency. The system can obtain a frequency diversity gain of the N fold by using a subset of carrier frequencies for each set of users so that the carrier spacing fs for each user k exceeds the coherence band amplitude. For example, in the frequency profile shown in Figure 8, a set of non-adjacent frequencies 42, 43 and 44 can be selected for a particular group of users. This frequency profile allows both time shifting and frequency division multiplexing to utilize bandwidth efficiency. If the bandwidth of each carrier is small compared to the separation fs of the carrier, an unauthorized intersection of the CIMA signal by a wideband receiver is more difficult. The amount of background noise received by a receiver depends on the bandwidth of the receiver. A CIMA receiver can be tuned to receive CIMA carriers in predetermined narrow bands in which the signal to noise ratio (SNR) is relatively large. However, a wideband receiver receives noise components in the spectrum between the CIMA carriers resulting in a low SNR. If the number of users k exceeds the number N of CIMA carriers, the regulation offset of each user k can be selected to place the CIMA pulses to minimize the average square cross-relations between the pulses. The user signals can also be placed in relation to the type of priority of each user communication channel. This ensures the quality of service for specific users or types of transmissions. This also provides the quality of a limited resource system when the number of users is at or below the classic limit of a limited resource system and provides limited interference separations when the demand exceeds a classical limit. Although the receiver shown in Figure 7 is described as a single-user receiver, a preferred mode of operation is multiuser detection. Unlike the direct CDMA sequence where each user contributes to the noise of the communication channel of the other users, the CIMA limits the interference of multiusers to use signals (pulses) that are close in the time domain. In the preferred mode of operation, the receiver takes samples adjacent to the user's signals in as few as two nearby user time slots. He then performs a weight and sum in step 66 of decision to cancel those contributions or the intended user signals. The spacing d between the antenna elements 24n of the transmitter 70 (shown in Figure 3) results in an azimuthal variation of the beam pattern produced by the directional antenna 24n due to the time-dependent phase separation characteristic of the CIMA signal . In other words, as the phase space of the CIMA signals changes over time, the beam pattern of the array 24n scans. The time dependence of the direction of the pattern is shown by the following beam pattern equation: Dit) = a "cos ((fl >; 0 +? + Ipndsin & I? -) n-l where an is the amplitude of each carrier CIMA,? 0 + n? S is the radial frequency of the carrier CIMA nth,? N is the wavelength of the carrier CIMA,? is the azimuth angle and d is the separation between the array elements 24n. This feature of the CIMA beam pattern can also improve the diversity benefits of CIMA. The prior art shows that by changing a beam pattern of an antenna transmitting aid in reception diversity. The diagrams of the beam pattern equation D (t) are shown in Figures 9A to 9L for d =? O / 2 and the increased values of time t. Different values for the separation d result in changes to the number of main lobes and the speed at which they explore. Adjusting the frequency separation fs changes the directionality D (t). Figure 10 shows a frequency change feedback cavity (FSFC) 70 that can be used to generate CIMA signals. A base frequency generator 72 produces a frequency fQ the optical base frequency from which frequency change signals are created. The base frequency signal is input into • the traveling wave cavity 74 which includes a frequency changer 76. The frequency changer 76 can be an acoustic-optical modulator (AOM). As the light circulates through the cavity 74, it changes in frequency by an amount fs each time it passes through the frequency changer 76. The traveling wave cavity 74 does not attenuate 4fl 10 selectively the frequencies. Instead, the oscillations it supports are characterized by an unusually broad spectrum result that has no mode structure. A portion of the light leaves the cavity to a multi-carrier processor 78. For example, an AOM (not shown) diffracts the light passing through it; the light is then fed back into the cavity 74. A non-diffracted portion of the beam provides a convenient result. The result of The processor 78 is transferred to an output coupler (not shown) for example, an antenna, a focusing element, a connector or an optical fiber. The output beam consists of multiple light beams of frequency change incrementally delayed. The amount of delay incurred by each output beam component is identified by the frequency of the component. If the cavity 74 does not cause the light to suffer a significant amount of chromatic dispersion, the amount of delay incurred by an output component is substantially • proportional to the amount of frequency change in which 5 the beam has incurred. The multicarrier processor 78 may include diffraction optics to multiplex the wavelength of the output components. If the base frequency generator 72 modulates the optical base signal with an information signal, the results of the multi-carrier processor 78 k 10 include multiple (and separate) delay versions of the modulated signal. Each of the delayed versions of the modulated signal can be used to modulate a transmission signal emitted by each of the directional antenna elements 24n shown in Figure 3. 15 If each directional array element 24n emits a transmission signal that has the same frequency distribution, the directionality of the beam pattern produced ^? by a directional arrangement 24n does not change in time. Instead, the directionality can be adjusted simply by changing the length of the traveling wave cavity 74. The FSFC70 can also be used as a receiver to sample the CIMA signals received in non-zero phase spaces. This requires that the change fs of frequency by the frequency changer 76 coincide with the frequency separation of the received CIMA signals. The light output of the FSFC 70 is separated by the wavelength to identify the different samples of phase spaces of • the CIMA signal. These phase spaces will be substantially linear if the cavity 74 does not cause chromatic dispersion. The linear phase space sampling agrees with the phase spaces of the received signals taking into account that f0 »N * fs. The FSFC 70 shown in Figure 10 can be used to generate CIMA signals for transmission through an optical fiber or a guide wave. In this mode of operation the frequency generator 72 produces an unmodulated optical base signal. The result of the traveling wave cavity 74 is a colmeal superimposition of CIMA carriers and it is easy to fit into an optical fiber. In this way, multi-carrier processor 78 does not separate the components. The multi-carrier processor 78 modulates the CIMA signals with an information signal having a predefined duration in the time domain. The time and duration of the signal Information may be chosen to compensate for the chromatic dispersion of the CIMA carriers as they propagate through the fiber. Chromatic dispersion occurs in an optical fiber as different wavelengths of light travel at different speeds. Fiber optic has different refractive indices for different wavelengths of light. The speed of light in the material is inversely proportional to the refractive index. In the dispersion of the material, light with a long wavelength travels faster than light with a shorter wavelength. This causes distortion (widening) of the optical points through the optical fiber. Figure 4 shows the phase relationship between the CIMA carriers as a CIMA signal propagates in a non-dispersing medium. As the CIMA carriers propagate through space, the CIMA pulses are not distorted because the phase relationship between the carriers does not change except for their periodic relationship. For example, a receiver that moves at the speed of the carriers does not detect changes in the relative phase of the carriers. Another way to describe this is that two static receivers can be separated by an integral number of pulse periods, and detect the same phase relationship between the CIMA carriers. However, in a dispersion medium, the two static detectors detect different phase relationships because some carriers have traveled further in the phase. The following equation shows the difference in wavelength between the adjacent CIMA carriers TO? = - cf. # ^ ~ /.(/ "+ /,) This and another non-linear relationship in which the difference ?? of wavelength between adjacent CIMA carriers increases to 5 that. the wavelength of each carrier increases. This is illustrated by a maximum carrier phase profile 123 in Figure 4. The frequency separation fs is selected with respect to the dispersion characteristics of the optical fiber 150 to coincide with • the velocity profile of the carriers with their phase profile. In followed the portions of the carriers are selected to constructively combine to create CIMA pulses at predetermined locations along the fiber 150. The CIMA carriers are modulated by pulse amplitude in a time slot 133 in which the profile 123 Phase 15 occurs. At that time the time intervals 133, the composite signal 130 resulting from the sum of the carriers is negligible. As the carriers propagate through the fiber 150, the relative phases of the carriers change. During a time interval 135 Subsequently, the carrier signal phases are aligned at a specific time 125, which results in constructive interference causing a pulse to occur in the composite signal 130. At subsequent time intervals 127, 129, the low wavelength carriers have traveled slightly further, resulting in distorted phase profiles 137, 139, respectively. The signal 130 composed in these time intervals is returned to zero. Figure 11 shows a plurality of composite CIMA signals along an optical dispersion fiber 150. Three signals 160 170 and 180 are inserted into one end of the fiber 150. The phase profile of the signal 160 is selected such that the CIMA carriers constructively combine to produce a pulse 161 in a first mode 151. The first CIMA carriers 160 are constructively combined to produce low level signals 162 and 163, in the second and third nodes 152 and 153, respectively. Likewise, the carrier phases of the second signal 170 are selected to produce a signal 172 that constructively interferes with the second node 152. Similarly, the carrier phases of the third signal 180 are selected to provide constructive interference 183 in the third node 153. By making use of the non-linear scattering of light in an optical fiber, it may be possible to expand the usable bandwidth of the optical fiber beyond the classical limits.

Figure 12A shows an amplitude distribution for twenty CIMA carriers. These carriers produce a combined signal shown in Figure 12B which consists of a pseudo-random sequence of positive and negative CIMA pulses. Thus, a particular distribution of carrier amplitudes in the frequency domain results in a direct sequence CDMA code that is periodic in the time domain. When CIMA signals are used as the basis for a CDMA system, the CDMA system gains the advantages of reduced multi-path and intersymbol interference such as increased capacity, and reduced co-channel interference. Because the CIMA signals are synchronization functions, they have a high autocorrelation efficiency. The. Autocorrelation function drops quickly when synchronization is lost. Preferred embodiments demonstrate some of the methods for generating and receiving CIMA signals. This is said to provide a basic understanding of the characteristics of CIMA. With respect to your understanding, many aspects of this invention may vary; for example, the methods used to create and process CIMA signals. It should be understood that such variations fall within the scope of the present invention, their essence being found more fundamentally with the realizations and design discoveries achieved than in the particular designs developed. The above discussion and the claims that follow describe the preferred embodiments of the present invention. Particularly with respect to the claims, it should be understood that changes can be made without departing from the essence of the invention. In this regard, it is intended that said changes still fall within the scope of the present invention. To the extent that such revisions utilize the essence of the present invention, each naturally falls within the protection included in this patent. This is particularly true for the present invention because its basic concepts and understandings are fundamental in nature and can be widely applied.

Claims (43)

1. CLAIMS 1. A method for communication between at least one transmitter and a receiver that uses multiple access communication signals from carrier interference 5 (CIMA), characterized in that the method comprises the steps of: • providing for the generation of a plurality of electromagnetic carrier signals that are used for at least one user, the carrier signals have a plurality of frequency ks, • provide a phase relative to the carriers to produce a predefined phase relationship in a predetermined time, • provide the modulation of the carrier signals by means of an information signal, • provide the transmission of the modulated phase carrier signals, in a communications channel for producing CIMA transmission signals having carrier signal components, and • providing the CIMA transmission signal reception of the channel wherein the carrier signal components are combined in phase to produce at least one conflicting interference pulse indicating the signal of information .
2. 2. The communication method according to claim 1, characterized in that the carrier signals are incrementally separated in frequency. • The communication method according to claim 1, characterized in that the step of providing the generation of a plurality of electromagnetic carrier signals includes the generation of a plurality of bearer groups having identical sets of carrier frequencies. Each group is assigned? K 10 to a plurality of users, and the step of providing a phase relative to the carriers includes providing a unique relative phase to the bearers of each group where each group has a unique time offset to generate beats which are received in different 15 time intervals. 4. The communication method according to claim 1, characterized in that the step of ^ B providing the generation of a plurality of electromagnetic carrier signals includes the generation of a plurality of carrier groups, each group having a unique set of carrier frequencies and being assigned to at least one user, and the step of providing a phase relative to the carriers includes providing a phase relative to each group so that a plurality of users receive pulses in the same time interval but each user uses different carrier frequencies. ^^ 5. The method of communication according to claim 1, characterized in that the step of 5 providing the generation of a plurality of electromagnetic carrier signals has a plurality of frequencies that includes the step of providing variations to the carrier frequencies with respect to the time wherein the frequency variations for each carrier in a group A 10 of carriers corresponding to each user are substantially identical, with this causing little or no change to the pulse envelope. 6. The communication method according to claim 1, characterized in that the step of 15 providing modulation of carrier signals comprises pulse amplitude modulation being applied to a plurality of carriers, pulse width modulation ^ p has a duration that is greater than the pulse width of constructive interference pulses. 7. The method of communication according to claim 1, characterized in that the step of providing modulation of the carrier signals comprises the pulse amplitude modulation being applied to a plurality of carriers, the pulse amplitude modulation has a duration which is shorter than the pulse period of constructive interference. The communication method according to claim 1, characterized in that the step of providing the generation of a plurality of electromagnetic carrier signals includes tapering the frequency versus amplitude window of the carrier signals to reduce the energy of the domain side lobe. Pulse time of constructive interference. 9. The communication method according to claim 1characterized in that the step of providing the reception of the CIMA transmission signals includes the step of providing a predetermined number of delays to each received carrier signal before combining to produce the constructive interference pulse where the number of predetermined delays equals the number of different phase spaces in which the received CIMA transmission signal is sampled. The method of communication according to claim 1, characterized in that the step of providing modulation of the carrier signals by an information signal is carried out in a specific time interval with respect to the phase of the carriers so that the carriers The resulting modulated ones occupy one or more non-zero phase spaces and are not constructively combined in a zero phase space to produce a pulse. The communication method according to claim 1, characterized in that the step of providing the CIMA transmission signal reception includes compensating the relative phases of the carriers in at least one of the non-zero phase spaces for to be able to combine the carrier signals in phase. 12. The method of communication in accordance with the ^? 10 claim 9, characterized in that the multi-user interference is sampled in the different phase spaces and then weighed and combined with a user signal intended to cancel the contributions of the multiuser interference in the intended user signal 15. 1
3. 3. The method of communication according to claim 1, characterized in that the step ofwhat. ^ providing the generation of a plurality of electromagnetic carrier signals is performed by a frequency change feedback cavity 20. The communication method according to claim 1, characterized in that the step of providing the reception of CIMA transmission signals is performed by a frequency change feedback cavity. 15. The communication method according to claim 1, characterized in that the channel of • Communications is a guide wave. 16. The communication method according to claim 15, characterized in that the electromagnetic carrier signals are optical signals and the guide wave is an optical fiber. 17. The communication method according to claim 10, characterized in that the steps of providing the generation of a plurality of electromagnetic carrier signals and providing a phase relative to the carriers to produce a predefined phase relationship are performed to match with the phases 15 relative between the carriers to the chromatic dispersion profile of the carriers in the guide wave so that the dispersion causes the carrier phases to have a • default phase relationship after propagating a predetermined distance in the guide wave. 18. The communication method according to claim 1, characterized in that the step of providing the transmission of the modulated phase carrier signals includes transmitting the bearers of a transmitting directional antenna wherein each bearer for a particular user is transmitted from a transmitting antenna. transmitting element separate from the directional antenna and a directional antenna beam pattern is generated from the superposition of the transmitted carriers of each of the transmitting elements. The communication method according to claim 18, characterized in that a separation between the transmitting elements is selected with respect to the carrier frequency separation to control the shape ^ P 10 of the directional antenna beam pattern and the period in which it explores the directional antenna beam pattern. 20. The method of communication according to claim 1, characterized in that the step of providing a relative phase with the carriers results in 15 a train of pulses in the time domain and the step of providing modulation of the carrier signals results in modulating each of the pulses with a frequency chip • direct so that the modulated pulse train is a direct sequence code. 21. The communication method according to claim 20, characterized in that the direct sequence chip is the product of an information signal and a chip of a pseudo-random CDMA propagation code. 22. The method of communication according to claim 1, characterized in that the step of providing the reception of the CIMA transmission signals includes the detection of multiusers in which the signals # of user of a intended user and at least one user 5 of interference are received where the interference user signals are weighed and combined with the intended user signals to cancel the interference user signals on the intended user signals. 23. The method of communication in accordance with 10 claim 1, characterized in that the step of providing a phase relative to the carriers to produce a predefined phase relationship in a predetermined time results in at least two constructive interference pulses received that overlap in time. 2
4. 4. The method of communication according to claim 1, characterized in that the step of providing a relative phase in the carriers to produce a predefined phase relationship in a predetermined time includes a decision step that allows At least two received constructive interference pulses overlap in time when the number of users or the channel usage increases beyond the predetermined limit. 2
5. 5. The communication method according to claim 24, characterized in that the decision step includes a step of identifying the users and assigning a priority to each user that is used to determine that • user signals will be selected to overlap in 5 time. The communication method according to claim 1, characterized in that the carrier frequencies for each user are separated by an amount that is equal to or greater than the coherence band amplitude of the • 10 communication channel. 27. A Carrier Interference Multiple Access Communication System (CIMA) for providing communication between at least one transmitter and a receiver characterized in that it comprises: • a CIMA transmitter comprising: a multi-carrier generator for generating a plurality of carrier signals electromagnetic that are used by at least one user in which the carrier signals are increasingly separated in frequency, a delay controller to cause a predefined phase relationship between the carriers in a predetermined time, a carrier modulator to modulate the carrier signals with an information signal, and an output coupler for coupling the modulated phase carrier signals in a communications channel to produce the CIMA transmission signals having carrier signal components • a CIMA receiver for receiving the CIMA transmission signals from the channel, providing a predetermined delay terminated for each of the carrier signal components and combining the carrier signal components in phase to produce at least one constructive interference pulse indicating the information signal. The CIMA communication system according to claim 27, characterized in that the CIMA receiver takes samples within at least a predetermined time interval to receive at least one pulse in the zero phase space. 29. The CIMA communication system according to claim 27, characterized in that the CIMA receiver samples a user signal in a plurality of phase spaces at different times and combines the samples in a signal evaluator which values the signal of information . 30. The CIMA communication system according to claim 27, characterized in that the CIMA receiver is a multi-user detector that samples one or more interference user signals that interfere with a intended user signal, weighs the interference signals shown, and combines the signals of • interference displayed with the intended user signal 5 to cancel multi-period interference. 31. The CIMA communication system according to claim 27, characterized in that the multi-carrier generator is a frequency change feedback cavity. • 32. The CIMA communication system according to claim 27, characterized in that the communication channel is a guiding wave. 33. The CIMA communication system according to claim 27, characterized in that the output coupler 15 is a directional array of transmitters. 34. The CIMA communication system according to claim 33, characterized in that each element • Directional antenna transmits a separate carrier signal for each user, thereby creating a time-dependent beam pattern for each user, and the multi-carrier generator controls the frequency separation of the carriers to control the scanning speed of each pattern of beam. 35. The CIMA communication system according to claim 27, characterized in that the carrier signals are not uniformly separated in frequency. 3
6. 6. The CIMA communication system according to claim 27, characterized in that one or more functions of at least one of the transmitters and the receiver are performed by digital signal processing. 3
7. 7. The CIMA communication system according to claim 27, characterized in that the receiver provides a gain adjustment to at least one of the carrier signal components to compensate for plane fading. 3
8. 8. The CIMA communication system according to claim 27, characterized in that the multi-carrier generator provides a tapered amplitude in the carriers to reduce the side lobes. 3
9. 9. The CIMA communication system according to claim 27, characterized in that the carrier modulator applies pulse amplitude modulation to the carrier signals. 40. The CIMA communication system according to claim 39, characterized in that the pulse amplitude modulation is applied in a predetermined time interval in relation to the carrier phases to produce one or more CIMA transmission signals occupying one or more nonzero phase spaces and they are not constructively combined in a zero phase space. • 41. The CIMA communication system in accordance with claim 40, characterized in that the communication channel is a guide wave and the frequency separation and the relative phases of the carriers within a modulated pulse amplitude envelope are selected for match the chromatic dispersion of the guide wave to • 10 cause a predetermined phase relationship between the carriers that occurs after propagating a predetermined distance in the guide wave. 42. The CIMA communication system according to claim 27, characterized in that the receiver is 15 a frequency change feedback cavity. 43. The CIMA communication system according to claim 27, characterized in that the multi-carrier generator provides a predetermined amplitude to each carrier signal to generate a pulse train that has 20 a direct sequence modulation. SUMMARY A wireless communication system transmits data in multiple carriers simultaneously to provide frequency diversity. Carrier interference causes a narrow pulse in the time domain when the relative phases of the multiple carriers are zero. The selection of the frequency and phase separation of the carriers controls the regulation of the pulses. Both, the time division of the pulses and the division of the frequency of the 'carriers achieve multiple access. Carrier interferometry is a base from which other communication protocols can be derived. Frequency jumps and carrier frequency changes do not change the pulse envelope if the relative frequency spacing and phases between carriers are conserved. Direct sequence CDMA signals are generated in the time domain by a predetermined selection of the amplitudes of the carriers. A sample can be made with each pulse in different phase spaces at different times. This allows communication in phase spaces that are not detectable with conventional receivers. The time-dependent phase relationship of the carriers provides an automatic scan of a beam pattern transmitted by a directional antenna. In waveguide communications, the carrier frequencies and the phase space can be matched to the chromatic dispersion of an optical fiber to increase the capacity of the fiber.