CN1688145A - Training sequence transmission method for communication system - Google Patents

Abstract

This invention discloses a transmission method for training sequence under a multi-area system and structure, among which, said multi-area system includes multiple areas using a same frequency resource, said method includes: 1, when users of each local area are relatively independent, the local areas use the same or different training parent sequences, the transmissions of the training signals on different emit antennas of each local area applies different phase-shifts or time-shifts of a same parent sequences, 2, when a mobile terminal moves from one area to another area and arrives at the border, the training parent sequence of the destination area applies the training parent sequence same with the source area and the training sequence of the destination has different phase shift or time shift to that on the antenna of the source area.

Description

Training sequence transmission method in a kind of communication system

Technical field

The present invention relates to the training sequence transmission method under a kind of multi-cell system and the architecture.

Background technology

In recent years, along with the continuous growth of mobile user data business demand, wireless communication system is just experiencing from the third generation (3G) three generations's (B3G) development backward.In the commercialization and the marketization that the mobile communication carrier and the equipment manufacturers of our times various countries are actively promoting 3G (Third Generation) Moblie, every industry or trade, the research and development of the B3G mobile communication system of high speed business also launch for having more high spectrum utilization and providing more for university and other scientific research institutions.In order to maximize the return of investment of operator on the frequency spectrum resource of preciousness, the B3G mobile communication system will have higher spectrum efficiency than system in the past to support the more business of high data rate (more than 100Mb/s).In addition, mobile communication system operator is desirably on the limited bandwidth resources and supports more user simultaneously with acceptable service quality (QoS).Therefore, system designer just must be in the face of the challenge of higher power system capacity.The key factor of restriction system capacity is that multiple access disturbs (MAI) in multi-user or many antennas transmit simultaneously.In the B3G broad-band channel, because the frequency selective fading of channel makes transmitting on the every antenna produce a plurality of output signals at receiving terminal, thereby cause intersymbol interference (ISI), make the MAI problem further worsen.Therefore, alleviate even eliminate the various common concerns that may technology be subjected to the various countries scholar of MAI and ISI.When using these technology, the characteristics of radio channels of many antenna experience are assumed that knownly as channel transfer functions (CTF) or channel impulse response (CIR), must pre-estimate out thus.A kind of method of widely used estimation wireless channel is periodically to send specific training signal at transmitting terminal, and these training signals are known for receiver.Based on training signal that is sent and corresponding received signal thereof, according to the estimation of certain criterion acquisition for channel.Theoretical research shows that the training sequence that sends on performance for estimating channel and each antenna is closely related, so the important theory problem in the channel estimation studies of being designed to of training sequence.

Present channel estimation technique both domestic and external is primarily aimed at single-cell environment, estimates MAI and the ISI in single sub-district in (JCE) technology elimination channel estimation process as adopting combined channel.Under single-cell environment, channel estimated accuracy can be weighed by channel estimating mean square error (MSE) and signal-to-noise ratio degradation degree (SNR degradation).MSE is defined as:

$\mathrm{\ϵ}=E\left\{\right|\underset{\‾}{\hat{h}}-\underset{\‾}{h}{|}^2\}.$

Mean square error is weighed estimated channel CIR in order to statistics ground

With real channel CIR hBetween difference.The signal-to-noise ratio degradation degree is defined as:

${\mathrm{\δ}}^{(u,n_F)}=\frac{{\mathrm{\γ}}_{\mathrm{ref}}^{(u,n_F)}}{{\mathrm{\γ}}^{(u,n_F)}},$

In order to weigh a certain subcarrier of a certain user u (or symbol) n _FNext plants the signal to noise ratio γ with reference to receiving terminal under the channel estimation methods (being generally single user's matched filtering method) _Ref ^{(u, nF)}Signal to noise ratio γ with receiving terminal under the channel estimation methods of being considered ^{(u, nF)}Ratio.

Theoretical research shows, under single-cell environment, (has identical length and power) under certain assumed condition as supposing the training sequence of launching on each antenna, if receiver adopts the JCE technology, well-designed training sequence can be eliminated MAI and the ISI in multi-user or the multi-antenna channel transmission fully, thereby obtain optimum channel estimating performance, i.e. Zui Xiao channel estimating mean square error and minimum signal-to-noise ratio degradation degree.For can eliminating the training sequence that transmits on each antenna of MAI and ISI fully and should have the time shift orthogonality at the multi-user or the multi-aerial transmission system of time domain expression; For can eliminating the training sequence that transmits on each antenna of MAI and ISI fully and should have the phase shift orthogonality at the multi-user or the multi-aerial transmission system of frequency domain presentation.

One of challenge that the B3G system is faced is a power system capacity.For traditional Cellular Networks, generally adopt the method for cell splitting to enlarge power system capacity.After cell size reduces, switch and the presence of intercell interference increase burden of system signaling.In order to realize best user experience, improve power system capacity, become a focus of future broadband wireless communication systems architectural study based on the architecture of many sub-districts.Many sub-districts architecture is made up of a plurality of adjacent sub-district of using the same frequency band resource.Its basic thought is that antenna is distributed in each hot zones in the sub-district.System's spaced antenna that Continuous Selection and each portable terminal is nearest communicates.Neighbor cell uses identical running time-frequency resource and the portable terminal in its coverage to communicate.

Because identical band resource is used in some sub-districts of the inside of sub-district architecture more than, has just brought new challenge for channel estimation technique.In many sub-districts architecture that three sub-districts shown in Figure 1 constitute, portable terminal 7 (MS7) is positioned at three sub-districts (Cell_1, Cell_2, Cell_3) common factor of Fu Gaiing; MS4, MS5, MS6 are in the common factor that two sub-districts (Cell_1 and Cell_3, Cell_2 and Cell_3, Cell_1 and Cell_2) cover respectively; And MS1, MS2, MS3 only are in a sub-district (be respectively Cell_1, Cell_2 are in coverage Cell_3).Suppose that Cell_1 is that MS7 distributes training resource I, because MS7 is in the border of three sub-districts, so the training resource I of Cell_2 and Cell_3 can not redistribute.That is to say that MS7 has taken the same training resource of three sub-districts.In like manner, MS4 takies the same training resource of Cell_1 and Cell_3; MS5 takies the same training resource of Cell_2 and Cell_3; MS6 takies the same training resource of Cell_1 and Cell_2.The training sequence design of MS7 will directly influence Cell_1, the precision of channel estimation of Cell_2 and Cell_3 sub-district.If training sequence designs badly, will be directly to Cell_1, all users of Cell_2 and Cell_3 cause MAI.

In sum, under the architecture of many sub-districts, be in two (or a plurality of) cell coverage areas portable terminal simultaneously with two (or a plurality of) sub-districts in a plurality of spaced antennas communicate, thereby a plurality of mobile subscribers in these two sub-districts are caused the multiple access interference.How to carry out the training sequence design under the architecture of many sub-districts in future, feasible " multi-plot joint optimization " by training sequence not only makes the MAI of each inside, sub-district and ISI effectively be suppressed, and the MAI of minizone also can be overcome well, will be B3G system design and use one of important topic that is faced under the architecture of following many sub-districts.

The patent of the training sequence designing technique aspect in the at present domestic and international wireless communication system has only related to the training sequence design under single sub-district.As:

1) international monopoly: Method for transmitting information in acommunication system, a communication and a wirelesscommunication device, the patent No. is WO02/43277 A1, is proposed by Nokia (Nokia Corporation).

2) United States Patent (USP): Method for reception of multicarrier signals andrelated apparatus, the patent No. is: US 6,208, and 695B1 is proposed by German Thomson-Brandt Co., Ltd.

3) international monopoly: Wireless communication system using blockfiltering and fast equalization-demodulation and method ofoperation, the patent No. is WO02/058271A2, is proposed by Raze Technologies company.

Summary of the invention

The present invention is intended to propose the transmission method of the training sequence under the architecture of a kind of many sub-districts, and in the method, identical frequency resource is used in each sub-district in the multi-cell system.

According to the present invention, the transmission method of the training sequence under a kind of multi-cell system and the architecture is provided, wherein said multi-cell system comprises a plurality of sub-districts, and identical frequency resource is used in these sub-districts, and described method comprises step:

(1) when the user of each sub-district is relatively independent, identical or different training auxiliary sequences is used in each sub-district, and the different phase shifts or the time shift of same training auxiliary sequence are adopted in the transmission of the training signal on the different transmit antennas in each sub-district;

(2) portable terminal from a sub-district when two cell boarders are moved and arrived in another sub-district, the training auxiliary sequence of sub-district, destination adopts the training auxiliary sequence identical with the cell-of-origin, and employed training sequence has different phase shifts or time shift on each antenna of destination training sequence and cell-of-origin.

The present invention is by design and selection to training sequence, and the multiple access in the reduction channel estimation process in each sub-district disturbs and the multiple access of minizone disturbs, thereby improves the performance and the capacity of system greatly.

Description of drawings

The training sequence that Fig. 1 shows under the architecture of many sub-districts distributes schematic diagram;

Fig. 2 shows the multi-user/multiaerial system that is expressed in time domain;

Fig. 3 shows the multi-user/multiaerial system that is expressed in frequency domain;

Fig. 4 shows and is applicable to that multi-antenna transmitting defeated training sequence in single sub-district generates schematic diagram.

Embodiment

Basic design of the present invention is to belong to identical or different training auxiliary sequence but training sequence with different phase shifts or time shift is gone out from a plurality of antenna transmission of a plurality of (two) sub-district at least.User in each sub-district is relatively independent, does not for example have portable terminal when a sub-district moves to the situation of another sub-district, and the design of training sequence can be carried out in each sub-district relatively independently.Different districts can use identical or different training sequence parent signal, but the transmission signal of the portable terminal in each sub-district comes from the different phase shifts or the time shift of same training sequence parent signal.As portable terminal from a sub-district to the motion of another sub-district and when arriving two cell boarders, to adjust the training sequence of one of them sub-district, the training auxiliary sequence that is the purpose sub-district adopts the training auxiliary sequence identical with the cell-of-origin, but different phase shift or the time shifts of training sequence on selection and employed each antenna in cell-of-origin.

The training sequence that sends on each antenna in many sub-districts adopts phase shift or time shift to be decided by the situation in the expressed territory of the training sequence signal in these sub-districts.Be expressed in the situation of time domain for training sequence, the training sequence in the sub-district adopts different time shifts.Time shift on concrete every transmit antennas and the multipath channel situation in the sub-district, factors such as user/number of antennas are relevant.Pairing multi-user of this situation or multiple antenna transmitter model are as shown in Figure 2.

Fig. 2 shows the multi-user/multiaerial system that is expressed in time domain.U transmitting antenna arranged in this system, and training sequence is expressed in time domain, is respectively time-domain training sequence 1, time-domain training sequence 2 to time domain training sequence U.Guard time can be the interval of any time between training sequence and the data.U training sequence U wireless channel of experience in the transmission of space, its channel impulse response is respectively h ⁽¹⁾, h ⁽²⁾With h ^(U)

Be expressed in the situation of frequency domain for training sequence, the training sequence in the sub-district adopts different phase shifts.Phase shift on concrete every transmit antennas and the multipath channel situation in the sub-district, factors such as user/number of antennas are relevant.Pairing multi-user/the multiple antenna transmitter model as shown in Figure 3 for this situation.

Fig. 3 shows the multi-user/multiaerial system that is expressed in frequency domain.U transmitting antenna arranged in this system, and training sequence is expressed in frequency domain, is respectively frequency domain training sequence 1, frequency domain training sequence 2 and frequency domain training sequence U.By contrary fast fourier transform (IFFT) frequency-region signal is converted to time-domain signal.Guard time can be the interval of any time between training sequence and the data.U training sequence U wireless channel of experience in the transmission of space, its channel impulse response is respectively h ⁽¹⁾, h ⁽²⁾With h ^(U)

For example for ofdm system, training sequence can be expressed in frequency domain, as shown in Figure 3.Under the architecture of many sub-districts, can send at the training sequence that above-mentioned two kinds of motion of mobile terminals situations select the different phase shifts of identical or different training sequence parent signal to be used on the different districts mobile terminal antenna.For WCDMA or TD-SCDMA system, training sequence generally is expressed in time domain, as shown in Figure 2.Under the architecture of many sub-districts, can send at the training sequence that above-mentioned two kinds of motion of mobile terminals situations select the different time shifts of identical or different training sequence parent signal to be used on the different districts mobile terminal antenna.

Below in conjunction with preferred embodiment training sequence transmission method of the present invention is described.

Suppose many community mobile communication systems of two sub-districts, adopt OFDM (OFDM) modulation technique with 16 subcarriers to carry out the transmission of signal in each sub-district, training sequence is expressed in frequency domain.The wireless fading channel of supposing each sub-district is four footpaths.The training sequence parent signal of every sub-district can be selected permanent amplitude zero auto-correlation for use, and (constant amplitude zeroautocorrelation, CAZAC) sign indicating number are 16 CAZAC sign indicating number sequence as length Can be configured to:

${\underset{\‾}{\overset{~}{c}}}_1={\left[\begin{array}{cccccccccccccccc}1& 1& 1& 1& 1& -j& -1& j& 1& -1& 1& -1& 1& j& -1& -j\end{array}\right]}^T,$

Also can be configured to

${\underset{\‾}{\overset{~}{c}}}_2={\left[\begin{array}{cccccccccccccccc}1& 1& 1& 1& 1& j& -1& -j& 1& -1& 1& -1& 1& -j& -1& j\end{array}\right]}^T.$

By first CAZAC sign indicating number And through matrix of its cyclic shift (phase shift) formation By second CAZAC sign indicating number And through matrix of its cyclic shift (phase shift) formation Matrix First classify the CAZAC sign indicating number as Circulation by this yard moves the 2-16 row that 1-15 position (phase shift) constitutes this matrix.

${\underset{\‾}{\overset{~}{A}}}_{c1}=\left[\begin{array}{cccccccccccccccc}1& j& -1& -j& 1& -1& 1& -1& 1& -j& -1& j& 1& 1& 1& 1\\ 1& 1& j& -1& -j& 1& -1& 1& -1& 1& -j& -1& j& 1& 1& 1\\ 1& 1& 1& j& -1& -j& 1& -1& 1& -1& 1& -j& -1& j& 1& 1\\ 1& 1& 1& 1& j& -1& -j& 1& -1& 1& -1& 1& -j& -1& j& 1\\ 1& 1& 1& 1& 1& j& -1& -j& 1& -1& 1& -1& 1& -j& -1& j\\ j& 1& 1& 1& 1& 1& j& -1& -j& 1& -1& 1& -1& 1& -j& -1\\ -1& j& 1& 1& 1& 1& 1& j& -1& -j& 1& -1& 1& -1& 1& -j\\ -j& -1& j& 1& 1& 1& 1& 1& j& -1& -j& 1& -1& 1& -1& 1\\ 1& -j& -1& j& 1& 1& 1& 1& 1& j& -1& -j& 1& -1& 1& -1\\ -1& 1& -j& -1& j& 1& 1& 1& 1& 1& j& -1& -j& 1& -1& 1\\ 1& -1& 1& -j& -1& j& 1& 1& 1& 1& 1& j& -1& -j& 1& -1\\ -1& 1& -1& 1& -j& -1& j& 1& 1& 1& 1& 1& j& -1& -j& 1\\ 1& -1& 1& -1& 1& -j& -1& j& 1& 1& 1& 1& 1& j& -1& -j\\ -j& 1& -1& 1& -1& 1& -j& -1& j& 1& 1& 1& 1& 1& j& -1\\ -1& -j& 1& -1& 1& -1& 1& -j& -1& j& 1& 1& 1& 1& 1& j\\ j& -1& -j& 1& -1& 1& -1& 1& -j& -1& j& 1& 1& 1& 1& 1\end{array}\right]$

Equally, matrix First classify the CAZAC sign indicating number as

Circulation by this yard moves the 2-16 row that 1-15 position (phase shift) constitutes this matrix.

${\underset{\‾}{\overset{~}{A}}}_{c2}=\left[\begin{array}{cccccccccccccccc}1& -j& -1& j& 1& -1& 1& -1& 1& j& -1& -j& 1& 1& 1& 1\\ 1& 1& -j& -1& j& 1& -1& 1& -1& 1& j& -1& -j& 1& 1& 1\\ 1& 1& 1& -j& -1& j& 1& -1& 1& -1& 1& j& -1& -j& 1& 1\\ 1& 1& 1& 1& -j& -1& j& 1& -1& 1& -1& 1& j& -1& -j& 1\\ 1& 1& 1& 1& 1& -j& -1& j& 1& -1& 1& -1& 1& j& -1& -j\\ -j& 1& 1& 1& 1& 1& -j& -1& j& 1& -1& 1& -1& 1& j& -1\\ -1& -j& 1& 1& 1& 1& 1& -j& -1& j& 1& -1& 1& -1& 1& j\\ j& -1& -j& 1& 1& 1& 1& 1& -j& -1& j& 1& -1& 1& -1& 1\\ 1& j& -1& -j& 1& 1& 1& 1& 1& -j& -1& j& 1& -1& 1& -1\\ -1& 1& j& -1& -j& 1& 1& 1& 1& 1& -j& -1& j& 1& -1& 1\\ 1& -1& 1& j& -1& -j& 1& 1& 1& 1& 1& -j& -1& j& 1& -1\\ -1& 1& -1& 1& j& -1& -j& 1& 1& 1& 1& 1& -j& -1& j& 1\\ 1& -j& 1& -1& 1& j& -1& -j& 1& 1& 1& 1& 1& -j& -1& j\\ j& 1& -j& 1& -1& 1& j& -1& -j& 1& 1& 1& 1& 1& -j& -1\\ -1& j& 1& -j& 1& -1& 1& j& -1& -j& 1& 1& 1& 1& 1& -j\\ -j& -1& j& 1& -j& 1& -1& 1& j& -1& -j& 1& 1& 1& 1& 1\end{array}\right]$

Be applicable to that the defeated training sequence of two sub-district multi-user/multi-antenna transmittings can be by matrix And/or

Some row form.

At first, suppose that each sub-district has only the situation of a mobile terminal/antenna.In this case, can selection matrix

Any row, as the 1st row as the transmission of the training sequence of sub-district 1, selection matrix Any row, as the 1st row as the transmission of the training sequence of sub-district 2.Also can selection matrix Or matrix In two row, transmit as the training sequence of two cell mobile terminals as the 1st row and the 5th row.Training sequence on two cell mobile terminals comes from identical or different matrix by the signal processing mode of receiver (still is that the combined channel of minizone is estimated as the channel estimating in the sub-district) with minimize the sub-district in and decide with the multiple access interference of minizone.For example, if channel estimating is independently carried out by the receiver in each sub-district, then select training sequence on two cell mobile terminals to come from the mode of different matrixes; Finish if channel estimating is united by the common controller/receiver of two sub-districts, then select training sequence on two cell mobile terminals to come from the mode of same matrix.

In addition, the relatively independent and portable terminal relative fixed of the signal processing in two sub-districts, the also situation that does not promptly have terminal to move to another sub-district from a sub-district, two sub-districts can adopt different CAZAC sign indicating numbers as

With

As the female sign indicating number of training sequence.As the situation that terminal moves to another sub-district from a sub-district, the mobile subscriber of these two sub-districts will adopt identical CAZAC sign indicating number.

Secondly, suppose that respectively there is the situation of two portable terminal/antennas each sub-district.In this case, can selection matrix Any two row, transmit as the training sequence on two portable terminals of sub-district 1 respectively as the 1st row and the 5th row, wherein the 1st classify the training auxiliary sequence as, the 5th classifies its phase shift as.Selection matrix Any two row, transmit as the training sequence on two portable terminals of sub-district 2 respectively as the 1st row and the 5th row, wherein the 1st classify the training auxiliary sequence as, the 5th classifies its phase shift as.Also can selection matrix Or matrix In four row, as the 1st row and the 5th row, the 9th row, the 13rd row transmit as the training sequence on four portable terminals in two sub-districts respectively, wherein the 1st classify the training auxiliary sequence as, other classify its phase shift as.Training sequence on two cell mobile terminals comes from identical or different matrix by the signal processing mode of receiver (estimating still to be that the combined channel of minizone is estimated as the combined channel in the sub-district) with minimize the sub-district in and decide with the multiple access interference of minizone.For example, if channel estimating is independently carried out by the receiver in each sub-district, then select training sequence on two cell mobile terminals to come from the mode of different matrixes; Finish if channel estimating is united by the common controller/receiver of two sub-districts, then select training sequence on two cell mobile terminals to come from the mode of same matrix.

In addition, the relatively independent and portable terminal relative fixed of the signal processing in two sub-districts, the also situation that does not promptly have terminal to move to another sub-district from a sub-district, two sub-districts can adopt different CAZAC sign indicating numbers as With As the female sign indicating number of training sequence.As the situation that terminal moves to another sub-district from a sub-district, the mobile subscriber of these two sub-districts will adopt identical CAZAC sign indicating number as the female sign indicating number of training sequence, but the training sequence that transmits on all user/antennas should adopt different phase shifts.

Fig. 4 is for the CAZAC sign indicating number being the training sequence generation schematic diagram of each sub-district of example.This training sequence maker has two RAM (random access memory), is respectively RAM1 and RAM2, and two registers group, is respectively RG1 and RG2.In RAM1, stored and had N _FThe training auxiliary sequence of individual symbol as Usually some symbols of CAZAC sign indicating number are floating numbers, can be expressed as the fixed-point number of n bit.Individual switch is arranged between RAM1 and RG1, and this switch is responsible for selecting the N to RG1 _FIndividual shift register input data.Starting stage, switch is connected to RAM1, makes the symbol of CAZAC sign indicating number send RG1 under the control of clock 1 (clock1) with being pursued symbol.In each clock cycle, the n bit symbol of CAZAC sign indicating number is sent to the n bit shift register of RG1.Through N _FThe individual clock cycle, all shift registers among the RG1 have all been filled data, the N of promptly original CAZAC sign indicating number _FIndividual symbol is deposited into RG1.Switch is connected to the feedback line of RG1 then, the output of last shift register is fed back to the input of first shift register by this feedback line.This feedback line can be finished matrix

The middle original CAZAC sequence that requires Cyclic shift.The output of each shift register among the RG1 all is connected to the shift register of RG2.And the output of shift register is controlled by clock 2 (clock2) among the RG2.N in beginning _F-1 clock cycle, under the control of clock 2, the not output from RG2 to RAM2.Up to N _FThe individual clock cycle, after all symbols of original CAZAC sequence all are sent to RG1, the output from RG2 to RAM2 is arranged.This output has formed the training sequence that transmits on first user/antenna.After the output of next RG2 appeared at W clock cycle, this output had constituted the training sequence that transmits on second user/antenna.Every W clock cycle, the symbol that is stored among the RG2 is output subsequently, the training sequence that transmits on all user/antennas in producing the sub-district.

This training sequence maker can be configured in the high-rise control, for example can be configured in the central control unit of this sub-district.Under the architecture of many sub-districts, also configurable central control unit in many sub-districts.Under suitable receiver algorithm, such training sequence generating mode can guarantee in the minimum sub-district and the multiple access of minizone disturbs.

Claims (6)

1, the transmission method of the training sequence under a kind of multi-cell system and the architecture, wherein said multi-cell system comprises a plurality of sub-districts, and identical frequency resource is used in these sub-districts, and described method comprises step:

(1) when the user of each sub-district is relatively independent, identical or different training auxiliary sequences is used in each sub-district, and the different phase shifts or the time shift of same training auxiliary sequence are adopted in the transmission of the training signal on the different transmit antennas in each sub-district;

(2) portable terminal from a sub-district when two cell boarders are moved and arrived in another sub-district, the training auxiliary sequence of sub-district, destination adopts the training auxiliary sequence identical with the cell-of-origin, and employed training sequence has different phase shifts or time shift on each antenna of destination training sequence and cell-of-origin.

2, depend on the expressed territory of training sequence signal in each sub-district according to the training sequence employing time shift that sends on the antenna that the process of claim 1 wherein in each sub-district or phase shift.

3, according to the process of claim 1 wherein when training sequence is expressed in time domain, the training sequence in the sub-district adopts different time shifts, and multipath channel situation and user/number of antennas in the sub-district are depended in the time shift on every transmit antennas.

4, according to the process of claim 1 wherein when training sequence is expressed in frequency domain, the training sequence in the sub-district adopts different phase shifts, and multipath channel situation and user/number of antennas in the sub-district are depended in the phase shift on every transmit antennas.

5, according to the method for claim 1, also comprise step:

In receiving equipment, utilize training signal on each transmitting antenna to carry out detection for transmission information.

6, according to the process of claim 1 wherein that the information that is sent to receiving equipment from the antenna of each sub-district transmits at Frame, and with described training sequence multiplexed resource.