CN101594671B - Wireless transmitting and receiving device and method - Google Patents
Wireless transmitting and receiving device and method Download PDFInfo
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- CN101594671B CN101594671B CN2009101505407A CN200910150540A CN101594671B CN 101594671 B CN101594671 B CN 101594671B CN 2009101505407 A CN2009101505407 A CN 2009101505407A CN 200910150540 A CN200910150540 A CN 200910150540A CN 101594671 B CN101594671 B CN 101594671B
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Abstract
A wireless device, method, and signal for use in communication of a wireless packet between transmitting device and a wireless receiving device via a plurality of antennas, wherein a signal generator generates wireless packet including a short-preamble sequence used for a first automatic gain control (AGC), a first long-preamble sequence, a signal field used for conveying a length of the wireless packet, an AGC preamble sequence used for a second AGC to be performed after the first AGC, a second long-preamble sequence, and a data field conveying data. The AGC preamble sequence is transmitted in parallel by the plurality of antennas.
Description
The application is that application number is 200410081858.1, the applying date be December 24 in 2004 day, be called the dividing an application of application for a patent for invention of " wireless transmission and receiving equipment and method ".
The related application cross reference
Present patent application is based on the current Japanese patent application No.2003-433347 that submitted on December 26th, 2003 and require its priority, here with reference to quoting its full content.
Technical field
The present invention relates to be respectively applied for the packet radio that use comprises preamble and data, in the mobile communication system of similar WLAN, send and receive the wireless transmission device and the radio receiver of wireless signal, and the radio communication method and the method for wireless reception that are used for this equipment.
Background technology
Institute of electrical and electronic engineers (IEEE) is just defining the WLAN standard that is called IEEE 802.11n now, and its target is to realize 100Mbps or above high-throughput.Very possible IEEE 802.11n will use and use a plurality of antennas in transmitter and receiver, be called the technology of multiple-input and multiple-output (MIMO).Need IEEE 802.11n and the standard IEEE 802.11a coexistence of using OFDM (Orthodoxy Frequency Division Multiplex).Therefore, need IEEE 802.11n wireless transmission device and receiving equipment to have so-called back compatible.
The wireless preamble that is used for MIMO has been introduced in the suggestion that people such as Jan Boer proposes in " Backwards Compatibility " IEEE802.11-03/714r0.In this suggestion, short preamble sequence is used for time synchronized, Frequency Synchronization and automatic gain control (AGC), long preamble sequence is used for estimated channel impulse response, signal field is indicated employed modulating mode in the packet radio, and is at first sent from single specific transmitting antenna at another signal field of IEEE 802.11n.Then, growing preamble sequence is sent from other three transmitting antennas.After being sent completely of preamble, send data by from all antenna transmission.
To first signal field, the preamble that is proposed is same as the preamble of regulation among the IEEE802.11a (wherein supposing single transmitting antenna) from short preamble.Therefore, when the radio receiver that meets IEEE 802.11a received the packet radio comprise the preamble that Boer proposes, they found that grouping is based on IEEE 802.11a.Thereby the preamble that is proposed that meets IEEE 802.11a and IEEE 802.11n can coexist IEEE 802.11a and IEEE 802.11n.
Usually, in radio receiver, the demodulation of received signal is carried out by Digital Signal Processing.Therefore, provide modulus (A/D) transducer at the equipment that is used for the analog signal that digitlization receives.A/D converter has input dynamic range (the enable level scope of the analog signal that will change).Therefore, be necessary to carry out automatic gain control (AGC), in the input dynamic range of A/D converter, to regulate the level of received signal.
Owing to use above-mentioned long preamble sequence that the estimation of channel impulse response is carried out by Digital Signal Processing, must use the signal that before long preamble sequence, sends to carry out AGC.In the preamble of Boer, use the short preamble sequence that sends from specific transmitting antenna, before growing preamble sequence to carry out AGC.That is, the incoming level of short preamble sequence is measured, and AGC is performed, and makes incoming level in the input dynamic range of A/D converter.By using the AGC of short preamble sequence, the long preamble sequence and the data that send from specific transmitting antenna can correctly be received.If it is all antennas are separated to arrange, then different inevitably from the incoming level of the signal of antenna transmission.Therefore, receive the long preamble sequence that sends from other three transmitting antennas when radio receiver, or during from the data of all antenna transmission, its incoming level can be much more high or low than the level that AGC obtained that uses the short preamble sequence that sends from specific transmitting antenna.The going up of input dynamic range that exceeds A/D converter when incoming level prescribed a time limit, and the output of A/D converter is saturated.On the other hand, the following of input dynamic range that is lower than A/D converter when incoming level prescribed a time limit, and serious quantization error appears in the output of A/D converter.In both cases, A/D converter can not be carried out suitable conversion, this negative influence the processing after the A/D conversion.
In addition, from all antenna transmission data.Therefore, during transfer of data, the excursion of incoming level further increases, and it has worsened the above-mentioned saturated and/or quantization error wherein of A/D converter output, thereby significantly reduces receptivity.
As mentioned above, in the preamble that Boer proposes, only use the short preamble sequence that sends from single transmitting antenna to carry out AGC at receiving terminal, this makes the variation that is difficult to handle the incoming level that may occur during from the signal of other antenna transmission with the MIMO pattern when reception.
Summary of the invention
According to one aspect of the invention, a kind of wireless transmission device is provided, be used for passing through wireless packet communications with radio receiver, comprising: a plurality of antennas; The signal generator of the signal of the packet radio that is sent out with generation, packet radio comprises: short preamble sequence is used for first automatic gain control (AGC); The first long preamble sequence; Be used to transmit the signal field of the information that relates to packet radio length; The AGC preamble sequence is used for the 2nd AGC that carries out after an AGC; The second long preamble sequence; And the data field that transmits data, wherein said AGC preamble sequence sends by a plurality of antennas are parallel.
Because the signal format that the present invention uses comprises the preamble that is used for the AGC that fine tuning receives at the MIMO from a plurality of antenna transmission, the incoming level of A/D converter can suitably be adjusted at short notice, thereby strengthen the receptivity of radio receiver, and reduce the quantity of the resolution bit (resolution bits) of A/D converter.
Description of drawings
Be merged in and constitute the accompanying drawing of a specification part, illustrate embodiments of the invention, and principle of the present invention is described with the embodiment of general description that provides above and embodiment given below.
The view of Fig. 1 illustrates the form of packet radio, comprises the AGC preamble that is used for radio communication that uses in one embodiment of the invention;
The module map of Fig. 2 illustrates the structure of wireless transmission device according to embodiment;
The module map of Fig. 3 illustrates the structure of radio receiver according to embodiment;
The module map of Fig. 4 illustrates the configuration example of the receiving element of the equipment of incorporating Fig. 3 into;
The curve chart of Fig. 5 illustrates the distribution of the received power of short-and-medium preamble of prior art and data;
The curve chart of Fig. 6 illustrates the distribution of the received power of short-and-medium preamble of embodiment and data;
The module map of Fig. 7 illustrates another configuration example of receiving element;
Fig. 8 A is the flow chart of the operation of explanation gain controller;
The flow chart of Fig. 8 B shows AGC operation and the 2nd AGC operation;
The module map of Fig. 9 illustrates radio receiver according to the modification of embodiment;
The module map of Figure 10 illustrates the configuration example of the receiving element of the radio receiver of incorporating Fig. 9 into;
The module map of Figure 11 illustrates the configuration example of the propagation path estimation unit that appears among Fig. 3;
The view of Figure 12 illustrates the configuration example of the AGC preamble that occurs among Fig. 1;
The view of Figure 13 illustrates other configuration example of the AGC preamble that occurs among Fig. 1; And
The view of Figure 14 illustrates wireless transmission device according to another embodiment of the invention.
Embodiment
Embodiments of the invention are described in detail with reference to the accompanying drawings.
Fig. 1 has illustrated the form of the packet radio of using in the first embodiment of the present invention.This form is the physical layer protocol data unit form of MIMO pattern, and interoperability and compossibility with the wireless station of IEEE802.11a are provided.
As from Fig. 1 saw, preamble comprises (PLCP) signal of the Physical layer convergence protocol (physical layer convergence protocol) that sends from antenna Tx1.The PLCP signal comprises short preamble sequence 101, the first long preamble sequence 102, the first signal fields (signal) 103 and secondary signal fields (signal 2) 104.Short preamble sequence 101 comprises some unit preamble SP.Long preamble sequence 102 comprises the unit preamble LP with corresponding predetermined length.Preamble LP is longer than preamble SP.
Short preamble sequence 101, the first long preamble sequence 102 and first signal field 103 meet IEEE 802.11a, and secondary signal field 104 is that new WLAN standard IEEE 802.11n is required simultaneously.First signal field 103 that meets IEEE 802.11a can be known as " legacy signal field ".Because secondary signal field 104 is for new high throughput wireless LAN standard provides, so can be called " high throughput signal field ".Protection GI at interval is inserted between short preamble sequence 101 and the long preamble sequence 102.
After the PLCP signal, the parallel AGC preamble 105A that sends is positioned to 105D from a plurality of antenna Tx1 to Tx4.Send AGC preamble 105A simultaneously from a plurality of antenna Tx1 to Tx4 to 105D.AGC preamble 105A is used to make receiving equipment can carry out meticulous AGC when carrying out MIMO communication to 105D.These preambles are unique to the AGC that fine tuning is used for receiving according to the MIMO pattern of IEEE 802.11n.Therefore, AGC preamble 105A can be known as " the short sequence field of high-throughput " to 105D.On the other hand, meet IEEE 802.11a, so can be known as " the short sequence field of tradition " owing to be used to the short preamble sequence 101 of thick AGC operation.
After 105D, the second long preamble sequence 106A is to 109A at AGC preamble 105A, and 106B is to 109B, and 106C is positioned to 109D to 109C and 106D.In an embodiment, the same signal sequence is used as AGC preamble 105A to 105D.Yet the unlike signal sequence can be used as AGC preamble 105A to 105D.Protection at interval GI is inserted into and constitutes the second long preamble sequence 106A to 109A, and 106B is to 109B, 106C to 109C and 106D between every couple of adjacent cells preamble LP of 109D.As described below, the second long preamble sequence 106A is to 109A, and 106B is to 109B, and 106C is orthogonality relation to 109C and 106D to 109D.The quantity of the unit preamble LP 106-109 of each transmitting antenna equals the quantity of transmitting antenna in the MIMO pattern.In order to distinguish two kinds of long preamble sequence, the first long preamble sequence that meets IEEE 802.11a can be known as " the long sequence field of tradition ".Because the second long preamble sequence 106-109 is for new high throughput wireless LAN standard provides, so can be known as " the long sequence field of high-throughput ".
To 109A, 106B is to 109B at each second long preamble sequence 106A, and after 109D, transmission data 110A's 106C that is respectively applied for the transmission from antenna Tx1 to Tx4 is positioned to the field (data) of 110C to 109C and 106D.The second long preamble sequence 106A is to 109A, and 106B is to 109B, and 106C is sent respectively to Tx4 from a plurality of antenna Tx1 to 109D simultaneously to 109C and 106D.
Referring now to the wireless transmission device of Fig. 2 description based on embodiment.At first, digital modulator 203 is by mixing the signal that transmission data 201 and the above-mentioned preamble of exporting from memory 202 form packet radio.The signal of thus obtained packet radio is sent to transmitting element 204A to 204D, and wherein they are through sending required processing, and for example, digital-to-analogue (D/A) is changed, and frequency inverted is to radio frequency (RF) frequency band (go up and become conversion) and power amplification.To corresponding to reference Fig. 1 described antenna Tx1 to a plurality of antenna 205As of Tx4 to 205D send consequential signal, wherein from each transmitting antenna 205A to 205D RF signal sent to radio receiver Fig. 3 shown in thereafter.In the following description, the antenna Tx1 shown in Fig. 1 is hereinafter referred to as antenna 205A to 205D to Tx4.
In an embodiment, the PLCP signal that comprises short preamble sequence 101, the first long preamble sequence 102, the first signal fields 103 and secondary signal field 104 shown in Fig. 1 is sent by the transmitting antenna 205A from the transmitting element 204A shown in Fig. 2.AGC preamble 105A is to 105D, the second long preamble sequence 106A is to 109A, 106B is to 109B, and 106C (is positioned in after the PLCP signal) as shown in Figure 1 to 109C and 106D to 109D, and data 110A sends to 205D by all transmitting antenna 205A to 110D.
In the radio receiver shown in Fig. 3, a plurality of reception antenna 301A receive the RF signal that sends from the wireless transmission device shown in Fig. 2 to 301D.Radio receiver can have a reception antenna or a plurality of reception antenna.Sent to receiving element 302A respectively to 302D by reception antenna 301A to the RF signal that 301D receives.Receiving element 302A all carries out various receptions to 302D and handles, such as changing (becoming conversion down) from the RF frequency band to BB (base band), automatic gain control (AGC), analog-to-digital conversion or the like, thereby generation baseband signal.
Be sent to channel impulse response estimation unit 303A to 303D and digital demodulator 304 from receiving element 302A to the baseband signal of 302D.These unit 303A is to the impulse response of corresponding propagation path between the radio receiver of the wireless transmission device of 303D estimation Fig. 2 and Fig. 3.The back can be described channel impulse response estimation unit 303A in detail to 303D.According to by unit 303A to institute's estimated channel impulse response that 303D provides, digital demodulator 304 demodulated base band signals, thus produce received data 305 corresponding to the transmission data 201 shown in Fig. 2.
More specifically, digital demodulator 304 has the equalizer of channel impulse response in its importation.According to institute's estimated channel impulse response, equalizer carries out balanced to proofread and correct the received signal that distorts in the propagation path.Digital demodulator 304 is also with the determined suitable timing demodulation equalizing signal of time synchronized, thus restoring data.
Receiving element 302A shown in Fig. 3 will be described now to 302D.Fig. 4 shows in detail the structure of receiving element 302A.Because other receiving element 302B has the structure identical with unit 302A to 302D, so only describe receiving element 302A.Become 401 times changes of transducer under the RF received signal quilt by reception antenna 301A reception and convert baseband signal to.At this moment, the RF signal can directly be converted to baseband signal, or can be converted to intermediate frequency (IF) signal earlier and then be converted to baseband signal.
Be sent to variable gain amplifier 402 by the baseband signal that becomes transducer 401 generations down, it is performed AGC at this, i.e. signal level adjustment.Output is sampled by A/D converter 403 and is quantized from the signal of variable gain amplifier 402.It is outer and be sent to gain controller 404 that output is sent to receiving element 302 from the digital signal of A/D converter 403.Gain controller 404 is carried out gain calculating according to the digital signal output from A/D converter 403, and the gain of control variable gain amplifier 402.The detailed process back of gain controlling can be described.
The operation that comprises the radio receiver shown in Fig. 3 and 4 that the packet radio of the preamble of form shown in Figure 1 carries out for reception is as described below.At first, radio receiver receives the short preamble sequence 101 that sends from the transmitting antenna 205A of Fig. 2, and then use corresponding to the baseband signal of short preamble sequence 101 and carry out the grouping rim detection, time synchronized, automatic frequency control (AFC) and AGC.AFC also is known as Frequency Synchronization.Can use known technology to carry out the grouping rim detection, therefore time synchronized and AFC do not provide associated description.AGC only is described below.
Suppose that here the level corresponding to the baseband signal of lacking preamble sequence 101, obtaining is X before the A/D conversion.If level X is high, the baseband signal that then is input to A/D converter 403 exceeds the upper limit of A/D converter 403 input dynamic ranges.As a result, from the output of the signal (digital signal) of A/D converter 403 by saturated and reduced the quality that signal receives.On the other hand, if level X is very low, from signal output (that is the digital signal that obtains by the A/D conversion) the serious quantization error of appearance of A/D converter 402.Thereby when level XL was very high or low, A/D converter 403 can not be carried out suitable conversion, thereby had significantly reduced the quality that signal receives.
For overcoming this problem, gain controller 404 is controlled the gain of variable gain amplifiers 402, and feasible level X corresponding to the baseband signal of lacking preamble sequence 101 is adjusted to desired value Z.If the input baseband signal has very high level so that make the output of A/D converter 403 be limited in its boundary level, if or it have utmost point low level, the gain of variable gain amplifier 402 may be controlled irrelevantly by a control and treatment.In this case, repeat gain controlling.As a result of, the level that is input to the baseband signal of A/D converter 403 can be adjusted to the value that belongs to A/D converter 403 input dynamic ranges.Thereby, use corresponding to the baseband signal of short preamble sequence 101 and suitably control the gain of variable gain amplifier 402, thereby carry out suitable A/D conversion to avoid reducing the quality that signal receives.
Among the embodiment of Miao Shuing, use from the digital signal output of A/D converter 403 and measure the needed incoming level of gain that is used to calculate variable gain amplifier 402 in the above.Yet this level measurement can use the analog signal that obtained before the A/D conversion to carry out.In addition, in IF frequency band or RF frequency band rather than BB, measure incoming level.
Radio receiver receives the first long preamble sequence 102 that sends from transmitting antenna 205A, and carry out the channel impulse response estimation, that is, use is estimated the response (frequency transfer function) of wireless transmission device to the propagation path between the radio receiver corresponding to the baseband signal of long preamble sequence 102.Because the signal that sends from transmitting antenna 205A has carried out aforesaid AGC, so when carrying out the estimation of channel impulse response, suitably adjust the level that is input to A/D converter 403.Therefore, for the signal that sends from transmitting antenna 205A, point-device digital signal obtains from A/D converter 403.Use the digital signal that obtains, the estimation of channel pulse can accurately be carried out.
Radio receiver receives first signal field 103 that sends from transmitting antenna 205A, and uses digital demodulator 304 and above-mentioned propagation path estimation result, and demodulation is corresponding to the baseband signal of first signal field 103.First signal field 103 comprises the information of the packet radio length of the data of indicating modulating mode and sending after preamble.First signal field 103 is the fields that transmit a kind of attribute information that relates to packet radio.At the packet radio duration of discerning according to the packet radio length information that is included in first signal field 103, radio receiver continues to use digital demodulator 304 demodulation.
Owing to provide the interoperability of standing from the packet format of short preamble sequence 101 to first signal fields 103,, and do not destroy packet radio so normal reception operation can be carried out in IEEE 802.11a station with IEEE 802.11a.In other words, meet another IEEE 802.11a wireless transmission of IEEE 802.11a standard and receiving equipment (tradition station) when receiving first signal field 103, the transmission signal that is under an embargo finishes up to packet radio, so that do not destroy packet radio.
Then, radio receiver receives the secondary signal field 104 that sends from transmitting antenna 205A.Secondary signal field 104 comprises identification information, and it is indicated corresponding to the standard except that IEEE 802.11a, for example the packet radio of IEEE 802.11n.In other words, follow-up AGC preamble 105A is to 105D in secondary signal field 104 indication, and second grows preamble sequence 106A to 109A, and 106B is to 109B, and 106C is the signal corresponding to for example IEEE802.11n to 109C and 106D to 109D.
The AGC preamble 105A that the radio receiver parallel receive sends from transmitting antenna 205A to 205D is to 105D.AGC preamble 105A to 105D by from sending short preamble sequence 101, the first long preamble sequence 102, the transmitting antenna 205A of first signal field 103 and secondary signal field 104 sends, and sends to 205D from the transmitting antenna 205B that does not up to the present send signal.Therefore, though the signal that uses certain incoming level to receive to send from transmitting antenna 205A (promptly, short preamble sequence 101, the first long preamble sequence 102, first signal field 103 and secondary signal field 104), however use the incoming level be different from from the level of the received signal of transmitting antenna 205A to receive AGC preamble 105A to 105D.In other words, after sending, the MIMO that uses a plurality of transmitting antennas changes incoming level.
As mentioned above, radio receiver receives secondary signal field 104 and uses digital demodulator 304 demodulation secondary signal fields 104, thereby identification is corresponding to the current wireless grouping of IEEE 802.11n.After this, digital demodulator 304 sends instruction to restart AGC, with meticulous adjustment receiving element 302A to 302D, thereby AGC preamble 105A is re-executed AGC to 105D.As a result of, the signal that sends from transmitting antenna 205A to 205D and receive to 302D at receiving element 302A by mimo channel is imported into A/D converter 403 with the incoming level of suitable adjustment.
That is, by use after A/D conversion as shown in Figure 4 acquisition corresponding to the level of AGC preamble 105A to the baseband signal of 105D, on variable gain amplifier 402, carry out gain controlling.Digital demodulator 304 sends instruction and is not limited to obtain the time of the decoded result of secondary signal field 104 to time of the AGC of 105D to bring into use AGC preamble 105A.For example, digital demodulator 304 for example can use matched filter to confirm that AGC preamble 105A receives to 105D, and then provide instruction to receiving element 302A to 302D to begin AGC.
Before Jan Boer proposition, in the preamble of description, only use short preamble sequence (tradition weak point preamble) to carry out AGC from single transmitting antenna transmission.Use is used for carrying out AGC from the incoming level of the signal of the antenna transmission that sends short preamble sequence.When radio receiver received signal from other three antenna transmission, this equipment was carried out gain controlling by using the gain that is obtained.
The distribution of the short preamble that the curve chart of Fig. 5 obtains when illustrating the preamble that proposes at use Jan Boer and the received power of data.Channel is in multi-path environment, has the delay expansion (duration of a data symbol is 4 microseconds) of 50 nanoseconds.From this accompanying drawing as can be seen, lacking the incoming level of preamble (the short preamble of tradition) and the ratio of Data Receiving level changes significantly.
For example, at the regional A of Fig. 5,, receive short preamble with high incoming level although the Data Receiving level is lower.Therefore, if adjust AGC according to the received power of short preamble, then the received power of data is lower than the received power of short preamble, thereby produces quantization error at A/D converter 403.In the area B of Fig. 5,, receive short preamble with low incoming level although the Data Receiving level is high.Therefore, if adjust AGC according to the received power of short preamble, then the output of A/D converter is saturated when data are imported.Accordingly, it should be understood that since in traditional mode the received power of data and short preamble be constant than not, make the receiving feature degeneration because of quantization error or A/D converter output are saturated.On the other hand, in an embodiment, all antenna 205A that send data-signal send AGC preamble 105A respectively to 105D to 205D.Fig. 6 shows the distribution of the received power of short preamble and data based on embodiment.Channel circumstance is identical with the situation of Fig. 5.
As shown in Figure 6, the received power of AGC preamble and data 110A are proportional basically to the received power of 110D.This incoming level that shows A/D converter is suitably adjusted, and makes comparison diagram 5 receive accuracy and is significantly strengthened.
Fig. 7 shows the modification of receiving element 302A.Usually, for detecting unknown signaling, variable gain amplifier 402 uses relatively large gain as initial value.Therefore, if, then must repeated gain control be stabilized up to gain when the gain of AGC preamble 105A initialization variable amplifier 402 when 105D is received.Modification shown in Fig. 7 provides memory 405.This memory 405 is stored in and uses short preamble sequence 101 to carry out the yield value that obtains after the AGC.When receiving AGC preamble 105A to 105D, if the initial value of setting in backup status is not returned in the gain of amplifier 402, but be used as its initial value from the gain that memory 405 reads, the situation of this storage numerical value is not used in contrast so, AGC can not only accurately be carried out, and finishes at short notice.
Then, describe the operation of gain controller 404 in detail with reference to the flow chart of Fig. 8 A.
When receive short preamble sequence 101 the time, receiving equipment begins AGC (step S1).
Then, be set at counter values (i) (step S2) to 0.
Then, with reference to counter values, determine that whether AGC is in elementary or intergrade section (step S3).At this moment, because counter values is 0, the answer that step S3 puts question to is a "Yes", thereby carries out step S4.
After this, determine whether preamble 105 just is received (step S4) now.In this case, owing to the head of short preamble sequence 101 as packet radio is received, the answer that step S4 puts question to is a "No", thereby carries out step S5.At step S5, set predetermined initial value.
At next procedure S6, the amplification coefficient of variable gain amplifier changes according to the initial value of setting.At next procedure S7, measure the incoming level of current short preamble sequence.Determine at step S8 whether the level of measuring is the suitable level (target level) of A/D converter.If the answer that step S8 puts question to is a "No", then process is carried out step S9.
At step S9, realize counter values, and then program turns back to step S3.At step S3, determine that i is not 0, program is carried out step S10.At step S10, use the level of measuring at step S7 to carry out gain calculating.
Thereby, repeat the circulation of S10 → S6 → S7 → S8 → S9, arrive target level up to incoming level.When incoming level arrives target level, set gain at step S11 and be written to memory 405, thus the AGC that end is carried out the signal that sends from antenna Tx1.The effect of " thick AGC " is played in the meticulous AGC operation (the 2nd AGC) that the next MIMO of the use AGC preamble 105 that the contrast back can be described receives, this AGC operation (AGC) to receiving equipment.
Receiving element 302A receives long preamble sequence 102, the first signal fields 103 and secondary signal field 104 then.Receiving element 302A starts the AGC that MIMO receives with AGC preamble 105.AGC is from step S1, and transfers to S2, S3 and S4.At step S4, because receiving element 302A is receiving AGC preamble 105, program is carried out step S12, thereby reads the gain values that is pre-written into memory 405, and heel step S6.After step S6, carry out above-mentioned same treatment.
Above-mentioned flow process is summarized as follows.At Fig. 8 B overview flow chart is shown.At first, receive short preamble sequence 101 (step S21) at radio receiver.Then, begin AGC operation (step S22) and for variable gain amplifier 402A to 402D setting gain (step S23).Then, the gain of setting is written to memory 405 (step S24).After AGC operation, then use by utilizing AGC preamble 105A that the MIMO technology sends from a plurality of transmitting antennas to begin the 2nd AGC operation (step S25) to the reception result of 105D.Then, with reference to the gain (step S26) of write memory 405 and be that each variable gain amplifier 402A sets new gain (step 27) to 402D.
Thereby when receiving AGC preamble 105A to 105D, gain does not turn back to the initial value of setting in backup status, but the gain that is stored in the memory 405 that is obtained by an AGC is used as initial value.Because this operation, AGC preamble 105A makes radio receiver can use in short-term the meticulous AGC of the long MIMO of execution in receiving to 105D.This meticulous AGC provides enough accuracy for MIMO receives.
Fig. 9 is the view of modification of radio receiver of the public execution AGC of diagram Fig. 3.Fig. 9 is different from Fig. 3, and wherein in Fig. 9, public receiving element 302 is provided for antenna 301A to 301D.
Figure 10 is shown specifically the receiving element 302 of Fig. 9.The structure of Figure 10 is different from the structure of Fig. 7, and wherein in Figure 10, single gain controller 404 and storage use the memory 405 of the gain values of short preamble sequence 101 acquisitions to be provided for antenna 301A jointly to 301D.
Particularly, antenna 301A to the output signal of 301D by under become transducer 401A and be input to A/D converter respectively to 402D to 401D and variable gain amplifier 402A.A/D converter 403A is imported into common gain controller 404 to the output signal of 403D.The gain of being determined by gain controller 404 is input to variable gain amplifier 402A jointly to 402D.For example, the gain that allows the highest level that is obtained to 403D by A/D converter 403A after the A/D conversion to be set at target Z can be input to variable gain amplifier 402A jointly to 402D.
Same in the receiving equipment shown in Fig. 9 and 10, digital demodulator 304 confirm the reception of short preamble sequence 101 and provide instruction to receiving element 302 to begin an AGC.Afterwards, digital demodulator 304 is confirmed the reception of secondary signal field 104 or AGC preamble 105, and provides instruction to two AGC of receiving element 302 with beginning MIMO receiving mode.
Thereafter, radio receiver is received in the second long preamble sequence 106A that sends to the AGC preamble 105A of 205D from transmitting antenna 205A to 109A after 105D, and 106B is to 109B, 106C to 109C and 106D to 109D.Form the second long preamble sequence 106A to 109A, 106B is to 109B, and the unit preamble LP of 106C to 109C and 106D to 109D is same signal with the unit preamble LP that preamble sequence 102 is grown in formation first basically.
In addition, the second long preamble sequence 106A is to 109A, and 106B is to 109B, and 106C is to use the Walsh sequence to carry out orthogonalized signal to 109C and 106D to 109D.In other words, in Fig. 1, the polarity of each unit preamble with symbol " LP " is opposite with the polarity of each the unit preamble with symbol " LP ".Radio receiver receives the second synthetic mutually long preamble sequence 106A to 109A, and 106B is to 109B, 106C to 109C and 106D to 109D.As described later, by the second long preamble sequence and Walsh sequence are multiplied each other the signal that reduction sends from transmitting antenna 205A to 205D.
The specific descriptions of channel impulse response estimation unit 303A to 303D will be provided.Figure 11 illustrates channel impulse response estimation unit 303A in detail.Because other estimation unit class is similar to estimation unit 303A, only describes estimation unit 303A.Channel impulse response estimation unit 303A comprises that estimation unit 501A to 501D, is used for estimating respectively the response of the antenna Tx1 of reception antenna 301A and wireless transmission device to the propagation path between the Tx4 (corresponding transmitting antenna 205A is to 205D).
In estimation unit 501A, the second long preamble sequence 106A that is received is to 109A, and 106B is to 109B, and 106C is stored in data storage 502A to 109C and 106D in 502D to 109D.Particularly, memory 502A storage is contained in the value of the signal that the long preamble sequence 106A in the second long preamble sequence obtains to 106D by hybrid packet.Similarly, memory 502B storage is by the value of the signal that mixes long preamble sequence 107A and obtain to 107D, memory 502C storage is by the value of the signal that mixes long preamble sequence 108A and obtain to 108D, and memory 502D stores by mixing the value of the signal that long preamble sequence 109A obtains to 109D.
Suppose that transmitting antenna 205A is h1 to the response of propagation path between 205D and the reception antenna 301A, h2, h3 and h4 are stored in data storage 502A respectively, 502B, the signal numerical value S among 502C and the 502D
502A, S
502B, S
502CAnd S
502DBe given as:
S
502A＝LP＊h1+LP＊h2+LP＊h3+LP＊h4 (1)
S
502B＝LP＊h1+LP＊h2-LP＊h3-LP＊h4 (2)
S
502C＝LP＊h1-LP＊h2-LP＊h3+LP＊h4 (3)
S
502D＝LP＊h1-LP＊h2+LP＊h3-LP＊h4 (4)
Thereafter, adder 505 addition multiplier 504A are to the multiplied result of 504D.In this case, by the given signal value S of equation (1) to (4)
502A, S
502B, S
502CAnd S
502DBe added.Can find out to (4) that from equation (1) the value h1 that has only channel impulse response between long preamble PL and marker antenna Tx1 (transmitting antenna 205A) and the reception antenna is still as addition results.If the unit preamble PL that forms long preamble sequence all is provided as the book-bit mode of wireless transmission device and radio receiver, then the received signal that can obtain according to the signal by mixing transmission from all transmitting antenna 205A to 205D is estimated the channel impulse response transmitting antenna 205A and the reception antenna 301A.
On the other hand, at estimation unit 501B, among 501C and the 501D, coefficient memory 503B, 503C and 503D store Walsh sequence (1,1 ,-1 ,-1) respectively, (1 ,-1 ,-1,1) and (1 ,-1,1 ,-1).As a result of, estimation unit 501B, 501C and 501D can estimate antenna Tx2 respectively, the channel impulse response between Tx3 and Tx4 (transmitting antenna 205B, 205C and 205D) and the reception antenna 301A.
As mentioned above, channel impulse response estimation unit 303A estimates the response of each transmitting antenna 205A to propagation path between 205D and the reception antenna 301A.Similarly, channel impulse response estimation unit 303B to 303C estimate transmitting antenna 205A to 205D and reception antenna 301B to channel impulse response between the 301C.
Using AGC preamble 105A in the AGC of 105D, the yield value of the variable gain amplifier 402 that the signal that use sends from single transmitting antenna 205A by utilization is adjusted is as initial value, carry out gain controlling, the result has realized meticulous and gain controlling fast.The example of AGC preamble 105A to 105D described now.Form each at Figure 12 (a) by the burst that comprises a plurality of time-domain samplings (10 samplings under Figure 12 situation), (b), (c) and (d) the AGC preamble 105A shown in is to 105D.For example, the AGC preamble 105A that sends from antenna Tx1 comprise sequence (a0, a1, a2 ..., a8, a9).
In addition, by the mobile sample of circulation in the time domain of individual signals sequence, be formed on Figure 12 (a), (b), (c) and (d) the AGC preamble 105A shown in is to 105D.Particularly, the burst that obtains by the mobile sample of circulation the time domain of the AGC preamble sequence that sends from certain reference antenna is the AGC preamble sequence from another antenna transmission.For example, the AGC preamble sequence 105B that sends from antenna Tx2 be (a1, a2 ..., a9, a0), it moves a sample by circulating and obtains, i.e. the time location of the sample of the AGC preamble 105A that sends from reference antenna Tx1.
Similarly, the AGC preamble 105C that sends from antenna Tx3 moves two samples by circulating and obtains, i.e. the time location of the sample of the AGC preamble 105A that sends from reference antenna Tx1.The AGC preamble 105D that sends from antenna Tx4 moves three samples by circulating and obtains, i.e. the time location of the sample of the AGC preamble 105A that sends from as a reference antenna Tx1.
If AGC preamble 105A is formed by mutual identical burst to 105D, they understand the phase mutual interference during sending so.According to multipath state or acceptance point, this interference can cause being similar to the electric field that occurs when directional antenna sends when carrying out.As a result of, can appear zero point.In other words, an acceptance point may occur, not have the AGC preamble to be received, and incoming level may accurately not measured at this acceptance point place.
In an embodiment, the multipath of burst (that is, AGC preamble 105A is to the 105D) formation that is obtained by the time location that moves its sample by circulating is produced intentionally.In this case, even the incoming level of certain sample is lowered owing to signal disturbs in the burst, the probability that reduction appears in the incoming level of other sample is also lower.Therefore, realize accurate incoming level measurement, this has strengthened the receptivity of radio receiver.For example, can realize the communication system of CSMA/CA (having the carrier wave detection multiple access that conflict is avoided) agreement without prejudice to regulation in IEEE 802.11.
Figure 13 (a) to (d) illustrates AGC preamble 105A other example to 105D.AGC preamble 105A shown in Figure 12 (a) to (d) is to move the time-domain signal sequence that the time location of its sample obtains by circulation each other to 105D.On the other hand, the AGC preamble 105A shown in Figure 13 (a) to (d) is the frequency-region signal sequence to 105D, and has the different frequency component.In Figure 13, f0 indicates subcarrier frequency to f15, and is with hatched subcarrier to transmit signal, and the subcarrier of shadow-free line does not transmit signal simultaneously.
For example, the AGC preamble 105A that sends from antenna Tx1 is by subcarrier f0, f4, and f8 and f12 form.Similarly, the AGC preamble 105B that sends from antenna Tx2 is by subcarrier f1, f5, and f9 and f13 form.The AGC preamble 105C that sends from antenna Tx3 is by subcarrier f2, f6, and f10 and f14 form.In addition, the AGC preamble 105D that sends from antenna Tx4 is by subcarrier f3, f7, and f11 and f15 form.The subcarrier that sends from antenna Tx1 is not by any other antenna transmission.Similarly, the subcarrier that sends from antenna Tx2 is not by any other antenna transmission.
In fact, AGC preamble 105A is sent out after it converts the time-domain signal sequence to by quick Fu Liye inverse transformation (IFFT) or discrete Fourier transform (DFT) to 105D.In wireless transmission device, as shown in figure 14, memory 202 is stored as the AGC preamble, is related to the data to frequency-region signal sequence shown in (d) as Figure 13 (a).The frequency-region signal sequence data that reads from memory 202 is converted to the time-domain signal sequence by IFFT circuit 206, and is input to digital modulator 203.Digital modulator 203 can be introduced the function of IFFT circuit 206.In addition, memory 202 can be stored time-domain signal sequence data (being converted by the frequency-region signal sequence data shown in Figure 13 (a) to (d)) in advance.In this case, do not need IFFT circuit 206.
Shown in (d),, do not comprise the same frequency component to the signal of Tx4 as Figure 13 (a), so can not have and arrive radio receiver mutually intrusively from antenna Tx1 because AGC preamble 105A interweaves 4 antenna upper frequencies to 105D.As a result of, radio receiver can be carried out accurate incoming level and measure, and therefore shows high receptivity.
The invention is not restricted to the foregoing description, but can be by not departing from the modified in various manners of scope.For example, in the embodiment shown in Fig. 2, digital-to-analogue (D/A) conversion is carried out respectively to 204D at transmitting element 204A.Yet, can be changed into by digital modulator 203 rather than transmitting element 204A and carry out this D/A conversion to 204D.Similarly, in the embodiment show in figure 3, modulus (A/D) conversion is carried out respectively to 302D at receiving element 302A.Yet, can be modified as by digital demodulator 304 rather than unit 302A and carry out this A/D conversion to 302D.
For packet format, short preamble sequence 101, the first long preamble sequence 102, the first signal fields (signals) 103 and secondary signal field (signal 2) 104 are sent from antenna Tx1 as shown in Figure 1.Yet, can send this preamble signal from least one transmitting antenna.Each second long preamble sequence can have the different frequency component to 105D as the AGC preamble 105A that Figure 13 (a) to (d) illustrates.
Those skilled in the art will find apparent that additional advantages and modifications.Therefore, the present invention is at the representative embodiment that is not limited to specific detail aspect its scope and illustrates here and describe.Correspondingly, under the prerequisite of essence that does not depart from defined total inventive concept or scope, carry out various modifications according to appended claims and equivalents thereof.
Claims (1)
1. wireless transmission device comprises:
A plurality of antennas;
Signal provides device, is configured for the signal that the packet radio that comprises the following is provided:
Short preamble sequence is used for first automatic gain control at the radio receiver place,
The first long preamble sequence is used for first estimation of the channel impulse response between wireless transmission device and the radio receiver,
Signal field is used to transmit the information that relates to described packet radio length,
The AGC preamble, second automatic gain that is used for carrying out after first automatic gain control at radio receiver place is controlled,
The second long preamble sequence is used for second estimation of the channel impulse response between wireless transmission device and the radio receiver; And
Transmitter, be configured to send described short preamble sequence, described first long preamble sequence and the described signal field, and grow preamble sequence by the parallel described AGC preamble and described second that sends of described a plurality of antennas by in described a plurality of antennas at least one.
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| KR101559295B1 (en) * | 2009-12-04 | 2015-10-12 | 삼성전자주식회사 | Communication systen using spartial division-mimo |
| PL2515452T3 (en) | 2009-12-18 | 2015-09-30 | Electronics & Telecommunications Res Inst | Method for sending/receiving data in a wireless packet communication system in which there is simultaneous communication with a plurality of terminals |
| KR101800171B1 (en) | 2010-03-12 | 2017-11-24 | 한국전자통신연구원 | Method and apparatus for transmitting/receiving packet in wireless communication system |
| KR101791985B1 (en) | 2010-03-12 | 2017-10-31 | 한국전자통신연구원 | Method and apparatus for transmitting/receiving packet in wireless communication system |
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| US6289000B1 (en) * | 2000-05-19 | 2001-09-11 | Intellon Corporation | Frame control encoder/decoder for robust OFDM frame transmissions |
| JP2002290177A (en) * | 2001-03-23 | 2002-10-04 | Matsushita Electric Ind Co Ltd | Receiver and automatic gain control method |
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