CN1525655A - Asymmetric forward/reverse transmission bandwidth - Google Patents

Abstract

The invention is a kind of wireless communication system, it uses the up and down chain to transmit code division multi-access information with different bandwidth. The larger bandwidth is several times of the lower bandwidth. The system demands the base station and user unit have two pseudo random code generator which can be controlled separately and timing. It cuts off the code series of the smaller velocity chain when the code series of the larger velocity chain is stopped, acquires the alignment of pseudo random frequency expansion code of up and down chain.

Description

Asymmetrical forward/reverse transmission bandwidth

Present patent application is to be that February 10, application number in 2000 are dividing an application of 00801367.5 Chinese patent application the applying date, and the corresponding international publication number of the latter is International Application PCT/US00/03332 of WO 01/59949.

The present invention relates to radio digital communication system, particularly a subscriber unit and code division multiple access (CDMA) system that the base station uses different bandwidth to communicate with one another.

Cdma system provides radio spectrum band-limited a kind of effective use, thereby compares with the communication system of using other technologies such as time division multiple access and frequency division multiple access, can carry out relatively large message transmission with less distorted signals.

In the CDNA communication system, mix with pseudorandom spread spectrum sign indicating number on the whole bandwidth of this system's use the information spread spectrum at the information signal on the reflector.Spread-spectrum signal is up-converted into the radiofrequency signal of transmission.By a receiver of identical recognition of PN code with the spread-spectrum signal down-conversion that is sent, and with this down-conversion signal with the employed identical pseudo noise code of original information signal spread spectrum is mixed, reproduce original information signal.

Fig. 1 illustrates a kind of cdma communication system of prior art.This communication system has a plurality of base stations 20 ₁, 20 ₂-20 _n, these base stations connect by the road communicating line road via a regional public switch telephone network (PSTN), are perhaps connected by a Radio Link.Each base station 20 ₁, 20 ₂20 _nThe transmission of use spectrum CDMA is with movable type that is provided with in its honeycomb fashion zone and station, onsite user unit 22 ₁, 22 ₂22 _nCommunication.

In the cdma system of a typical prior art, the downlink bandwidth that use to the subscriber unit transmission base station is identical with the uplink bandwidth that subscriber unit uses to base station transmits.When the data volume of up link and down link equated substantially, for example under the situation of voice communication, the distribution of this symmetry of bandwidth was suitable.Yet in some signal intelligence, to the equal bandwidth of transmission distribution of uplink and downlink link, for the limited radio spectrum that a radio communication supplier is had, service efficiency is lower.For example, the general transmission of the user of internet usage may comprise the address, queried for items of the Internet and to the limited amount data of the key entry answer of inquiry etc.On the contrary, the server of a Internet is generally replied a customer requirements, and this user receives a large amount of texts, figure and other forms of data.At this moment, provide bigger downlink bandwidth, provide less uplink bandwidth, can make the whole bandwidth of distributing obtain more effective use like this to the communication supplier to the transmission link from user to the base station to the transmission link from the base station to user.Though during the whole bandwidth of using in the asymmetrical bandwidth communication situation identical with the uplink and downlink link bandwidth is consistent, but in asymmetrical communication, under the situation of the performance of not sacrificing the up channel that sends the finite data amount with lower speed, by using more down channel to occupy bigger bandwidth, can send data quickly.

In the cdma system of a typical prior art, a subscriber unit produces the pseudorandom spread spectrum sequence that per 29,877,120 clock cycle repeat.Whole sequence is called epoch (epoch) technically.Fig. 2 illustrates a kind of prior art system 200 that produces a pseudo random sequence.One data clock 202 is offered a first code generator 204, and it produces the pseudo random sequence of one 233,415 chip, and offers a second code generator 206, and it produces the pseudo random sequence of one 128 chip.The output combination of these two generators produces 233,415 * 128=29,877,120 pseudo random sequences that chip is long.In the ending of this sequence, code generator 204 and 206 makes code restart from the beginning of sequence.

When a subscriber unit began to transmit first, its pseudo random sequence was free-running operation.Its epoch is asynchronous with the epoch of the pseudo random sequence that takes place in the base station.Therefore, the beginning of the pseudo noise code of necessary search subscriber unit, base station, this is a time consuming process.

In above-mentioned a kind of prior art system, the use of different bandwidth means, the pseudorandom spread spectrum sequence for the uplink and downlink link with different speed timing controlled.Fig. 3 illustrates the epoch starting point of up link 120 and down link 100, in this down link clock rate twice that is up link.As shown in the figure, the starting point 122 of uplink signal time of occurrence and 124 is alignd with the epoch starting point 102 and 106 of down link every one.This produces a kind of ambiguity, that is, the subscriber unit of the down link data of decoding is not known the beginning of down link signal time of occurrence.For the transmission of a down link that begins in the uplink signal time of occurrence, the epoch of described up link starts from 122, and the starting point of down link may be 102 or 104.This ambiguity makes the whole sequence of subscriber unit search find starting point.This process expends the plenty of time that can not receive, and makes that therefore it is unpractiaca using asymmetric bandwidth like this.

Therefore, need a kind of cdma system, in such system, when the bandwidth of up link was different from the bandwidth of down link, the pseudorandom spread spectrum sign indicating number of uplink and downlink link was still synchronous.

The invention enables and to carry out the unequal cdma communication of uplink and downlink link transmission bandwidth.When uplink and downlink interchannel information transmitted amount was disproportionate, the asymmetrical distribution of transmission bandwidth had superiority.In system of the present invention, bigger bandwidth must be the integral multiple of less bandwidth.This system comprises a base station and a subscriber unit, and they respectively have two pseudo random code generators that can separate regularly, and two data clocks independently are with the modem interface that can read and write data with different speed.By blocking sign indicating number sequence when the termination of a complete code sequence of higher speed link, obtain the alignment of uplink and downlink link pseudorandom spread spectrum sign indicating number than the low velocity link.

By the detailed description of the following preferred embodiment of the present invention, objects and advantages of the present invention can be more clear.

Fig. 1 is the explanation of the cdma system of prior art;

Fig. 2 is the block diagram of the pseudo-random code sequence generator of prior art;

Fig. 3 is the schematic diagram of extended code epoch of the uplink and downlink link of different bandwidth in the prior art systems;

Fig. 4 is the schematic diagram of extended code epoch of uplink and downlink link of the different bandwidth of prior art systems;

Fig. 5 is the block diagram of a pseudo-random code sequence generator formed according to the present invention;

Fig. 6 is the block diagram of a base station formed according to the present invention.

Preferred embodiment is described with reference to the accompanying drawings.Same numeral among all figure is represented components identical.

The present invention allows to communicate in a cdma system, and the uplink and downlink link bandwidth of described system is different, and each other in integral multiple.The problem of Fig. 3 explanation is, in a side of communication, for example the epoch of the pseudo-random code sequence of down link 100 is than the opposite side of communication, and for example up link 120 causes the ambiguity of epoch starting point in short-term.Pseudo-random code sequence by the less bandwidth side that will communicate by letter when the termination of the epoch of bigger bandwidth side blocks, and solves this problem.

Fig. 4 illustrates the epoch starting point of up link 420 and down link 400, the twice that down link clock rate wherein and bandwidth are up link.As shown in the figure, the starting point 422 and 424 of the pseudo random sequence 430 of up link is every to align with the starting point 402 and 406 of down link pseudo random sequence 410 completely alternately completely.For the alignment between the starting point that remains on each pseudo random sequence, the present invention blocks less bandwidth signal on the point 426 that the sequence of the down link of higher repetition rate is restarted pseudo random sequence.So, in the present invention, have less bandwidth and produce a pseudo random sequence of blocking 428 with the side of communicating by letter than small data rate, the latter is included in the part of the number of chips that exists in the complete pseudo-random code sequence 430.In example shown in Figure 4, descending and bandwidth ratio up link is 2: 1.Therefore, the pseudo random sequence of up link 428 should comprise number of chips in the sequence 430 completely just in time half.In bandwidth ratio is 3: 1 o'clock, less bandwidth sequence be this completely sequence 1/3rd, the rest may be inferred to other bandwidth ratio.

See Fig. 5, at pseudo-random sequence generator 500 this illustrate, it can produce a sequence of blocking according to the present invention.Pseudo-random sequence generator 500 comprises 508, one resetting means 510 of 502, one counters of a data clock and two pseudo random code generators 504 and 506.Those skilled in the art understands, and the required number of clock cycle depends on the communication side that has big bandwidth.Therefore this counting is input to counter 508 via a counting incoming line 512.Counter 508 is loaded, and calculates the number by the clock cycle of data clock 502 outputs.When the requirement of having passed through the clock cycle several, counter 508 sends signal to resetting means 510, and two code generators 504 and 506 are resetted.

The pseudo random sequence that generator 504 takes place contains 223,415 chips.This sequence can be by 3,5, and 7,9,13 and 19 divide exactly.The pseudo random sequence that is produced by generator 506 contains 128 chips.This sequence can and divide exactly less than 128 2 multiple by 128.Therefore, the complete pseudo random sequence of 29,877,120 chips can be by 2,3, and other combinations of 4,5 and 128 and 223,415 the factor are divided exactly.To the bandwidth ratio of the Uplink/Downlink that mates these factors, can accurately block complete sequence.The invention enables and when the high bandwidth side is finished its pseudo-random signal time of occurrence, to finish its pseudo-random signal time of occurrence that blocks in the low bandwidth side of communication.

Fig. 6 illustrates according to a base station 300 of the present invention.Base station 300 comprises 302, one transmitter portion 304 of a receiver part and a modem interface unit 318.Modem interface 318 is provided at the receiver part 302 of base station 300 and an interface between transmitter portion 304 and the user.Modem interface unit 318 has a structure and the clock control that can read and write data with different speed.This differently can reach with adjustable clock speed by using.These design detailss are that those skilled in the art is known.

Antenna 306 receives the signal of subscriber unit, and this signal is by band pass filter 308 filtering.The output of filter 308 is downconverted into the baseband signal of the local oscillator that uses fixed frequency (Fc) by frequency mixer 310.The output of frequency mixer 310 is by applying a pseudo random sequence on the frequency mixer 312 in pseudorandom receiver (Rx) sequencer 314, on each modulator-demodulator by spreading spectrum and decoding.The output of frequency mixer 312 sends to modem interface unit 318 then.

In order to launch, 318 receive a baseband signal from the modem interface unit.Preferably use adaptive differential pulse-code modulation (ADPCM) signal of 32 (kb/s).This ADPCM or pulse-code modulation (PCM) signal is added to the frequency mixer 322 in pseudorandom reflector (Tx) sequencer 324.Frequency mixer 322 multiplies each other ADPCM or PCM data-signal and pseudorandom Tx sequence.The output of frequency mixer 328 is added to low pass filter 326.The output of filter 326 is added to frequency mixer 328, and suitable up-conversion.The signal of up-conversion is by band pass filter 330, to the wideband radio frequency amplifier 332 of driven antenna 334.Though illustrated is two antennas 306 and 334, preferred embodiment comprises a duplexer and the only antenna that is used to transmit and receive.

Digital signal processor (DSP) 336 control search procedure and pseudorandom Rx and Tx sequencer 314 and 324.According to the present invention, pseudorandom Rx and Tx sequencer 314 and 324 are by the DSP 336 independent clocks of controlling respectively.Therefore, the data clock (not shown) of pseudorandom Rx and Tx sequencer 314 and 324 be separately and independently.

In order to set up a link, base station 300 and subscriber unit must know what spreading rate uplink and downlink link 120 and 100 uses.When each call setup, can be between base station 300 and subscriber unit by sending the message that contains this information each other, to exchange this information.In addition, comprising this information of the spreading rate that uplink and downlink link 120 and 100 transmission are used, also can be a system parameters of programming in subscriber unit and base station 300.

Though the present invention at length is illustrated by specific embodiment, these details are in order to illustrate, are not determinate.Those skilled in the art will appreciate that in the spirit and scope that do not depart from this paper instruction and explanation, can carry out various changes structure and working method.

Claims (16)

1. communication system of in the uplink and downlink data link, all utilizing the extended code sequence, described system comprises:

Downlink data link with first bandwidth utilizes described first bandwidth, transmits the code sequence of first repetitiousness with first data rate;

Up data link with second bandwidth utilizes described second bandwidth, transmits the code sequence of second repetitiousness with second data rate, and described second bandwidth is greater than described first bandwidth;

With first generator of described downlink communication, described first generator is exported described first code sequence; And

With second generator of described uplink communication, described second generator is exported described second code sequence, wherein when described second code sequence is heavily covered each time, promptly blocks described first code sequence.

2. system according to claim 1, wherein said second bandwidth are the integral multiples of described first bandwidth.

3. system according to claim 1, wherein said system are a kind of code division multiple access (CDMA) communication systems.

4. communication system of in the uplink and downlink data link, all utilizing the extended code sequence, described system comprises:

Downlink data link with first bandwidth utilizes described first bandwidth, transmits the code sequence of first repetitiousness with first data rate;

Up data link with second bandwidth utilizes described second bandwidth, transmits the code sequence of second repetitiousness with second data rate, and described first bandwidth is greater than described second bandwidth;

With first generator of described downlink communication, described first generator is exported described first code sequence; And

With second generator of described uplink communication, described second generator is exported described second code sequence, wherein when described first code sequence is heavily covered each time, promptly blocks described second code sequence.

5. system according to claim 4, wherein said first bandwidth are the integral multiples of described second bandwidth.

6. system according to claim 4, wherein said system are a kind of code division multiple access (CDMA) communication systems.

7. communication system of in the uplink and downlink data link, all utilizing the extended code sequence, described system comprises:

The base station;

Subscriber unit is by downlink data link and up data link with second bandwidth and the described base station communication with first bandwidth; Described downlink data link utilizes described first bandwidth, transmits the code sequence of first repetitiousness with first data rate; It is to utilize described second bandwidth for described up data link, transmit the code sequence of second repetitiousness with second data rate, and described second bandwidth is greater than described first bandwidth;

With first generator of described downlink communication, described first generator is exported described first code sequence; And

With second generator of described uplink communication, described second generator is exported described second code sequence, wherein when described second code sequence is heavily covered each time, promptly blocks described first code sequence.

8. system according to claim 7, wherein said second bandwidth are the integral multiples of described first bandwidth.

9. system according to claim 7, wherein said system are a kind of code division multiple access (CDMA) communication systems.

10. communication system of in the uplink and downlink data link, all utilizing the extended code sequence, described system comprises:

The base station;

Subscriber unit is by downlink data link and up data link with second bandwidth and the described base station communication with first bandwidth; Described downlink data link utilizes described first bandwidth, transmits the code sequence of first repetitiousness with first data rate; It is to utilize described second bandwidth for described up data link, transmit the code sequence of second repetitiousness with second data rate, and described first bandwidth is greater than described second bandwidth;

With first generator of described downlink communication, described first generator is exported described first code sequence; And

With second generator of described uplink communication, described second generator is exported described second code sequence, wherein when described first code sequence is heavily covered each time, promptly blocks described second code sequence.

11. system according to claim 10, wherein said first bandwidth are the integral multiples of described second bandwidth.

12. system according to claim 10, wherein said system are a kind of code division multiple access (CDMA) communication systems.

13. a communication means that all utilizes the extended code sequence in the uplink and downlink data link, described method comprises:

Distribute first bandwidth to give the downlink data link;

Distribute second bandwidth to give up data link, described second bandwidth is greater than described first bandwidth;

Impose the code sequence of first repetitiousness, with in down link with the first data rate transport data;

Impose the code sequence of second repetitiousness, with in up link with the second data rate transport data; And

When described second code sequence is heavily covered each time, promptly block described first code sequence.

14. method according to claim 13, wherein said second bandwidth are the integral multiples of described second bandwidth.

15. a communication means that all utilizes the extended code sequence in the uplink and downlink data link, described method comprises:

Distribute first bandwidth to give the downlink data link;

Distribute second bandwidth to give up data link, described first bandwidth is greater than described second bandwidth;

Impose the code sequence of first repetitiousness, with in down link with the first data rate transport data;

Impose the code sequence of second repetitiousness, with in up link with the second data rate transport data; And

When described first code sequence is heavily covered each time, promptly block described second code sequence.

16. method according to claim 15, wherein said first bandwidth are the integral multiples of described second bandwidth.

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