CN1689245A - Adaptive chip equalizers for synchronous DS-CDMA system with pilot sequences - Google Patents

Abstract

A system and method for communicating over a single communication channel in a Direct Sequence- Code Division Multiplex (DS-CDMA) communication system. A pilot signal normally used for synchronization and channel estimation is now used as a training sequence for a chip-equalizer implemented in a mobile handset receiver device. The pilot sequence is always present in the data stream and may be continually used for equalizer adaptation at the mobile handset receiver. The method of using a pilot sequence(s) in order to adapt the taps of a chip equalizer occurs prior to despreading the user data. Additionally, a plurality of pilot sequences each having a known chipping sequence are generated and transmitted for continuous equalizer adaptation at the mobile handset receiver. The plurality of pilots received enables greater adaptation speed, thus enabling efficient tracking of fast varying channels. The method implements a least squares algorithm for enabling fast adaptation in rapidly fading channels using multiple pilot sequences.

Description

Be used to adaptive chip equalizers with the synchronous DS-CDMA system of pilot frequency sequence

Field that the present invention belongs to

The present invention relates to wireless communication system, relate to the system and method that is used for carrying out the adaptive code chip equalization especially in the DS-CDMA system that has pilot frequency sequence.

Background technology

For many years, the Multiuser Detection that is used for cellular CDMA-system is a very active research field always, and problem multi-user wherein that most of research is devoted to solve up link is not a mutually orthogonal.The method that is used for up link that finds out is to adopt the mode of centralized calculation, because base station receiver is not responsive especially for expense.Simultaneously, because all users of demodulation are wanted in the base station, therefore parallel and successful interference cancellation techniques is necessary.

In terminal, because price still generally adopts RAKE receiver, because terminal is subjected to the restriction of computational complexity.Therefore, just got rid of the employing interference cancellation techniques.List reference: A.Klein below, " Data Detection Algorithm that is used for cdma wireless mobile system down link " IEEE 47.VTC annual report, first volume 203-207 page or leaf, in May, 1997, K.Hooli, M.Latva-aho, and M.Juntti, " multiple access of the linear chip equalization device in the WCDMA descending link receiver disturbs and suppresses " IEEEGLOBECOME 99, the 1 volume 467-471 pages or leaves, in December, 1999.These have confirmed to compare in the gain aspect the capacity with descending link receiver expansion formerly after having used linear chip equalizer.But do not mention the problem of adaptive algorithm.At list of references G.Caire and U.Mitra, " the pilot tone adaptive M MSE receiver of DS/CDMA " IIC99I, first volume 57-62 page or leaf, in June, 1999, described a kind of adaptation method that uses pilot frequency sequence to eliminate interference, wherein estimated to replace reverse channel response with channel response.The structure of receiver is confirmed as not being based on the equalizer of chip but a traditional multi-user detector that utilizes channel metrics.At M.K.Tasatsanis, " cdma system inverse filtering standard " IEEETran.Signal Proc., the 45th volume 102-12 of first, in January, 1997, studied the inverse filtering of CDMA, and, emphasis is about the blind spot method, and it is very slow that this method seems in fast fading channel usually.Chip equalizer is equally also being studied, with reference to P.Komulainen, M.J.Heikkil  and J.Lilleberg, " adaptive channel equalizer of CDMA down link and interference suppress ", IEEE 6 ^ThInt.Symp. about spread spectrum Tech﹠amp; Appln., the second volume 363-367 page or leaf, in August, 2000 .P.Krauss, W.J.Hillery and M.D.Zoltowski, " the MMSE equilibrium of 3G CDMA forward link: symbol level is than chip-level " IEEE working group statistics.Signal and array proceedings, the 1st volume 18-22 page or leaf, in August, 2000; And M.J.Heikkil , P.Komulaincen, and J.Lilleberg, " in the CDMA down link, suppressing noise ", IEEE VTC Proceedings, the 2nd volume, 978-982 page or leaf, in August, 1999, in August, 2000 by adaptive channel equalizer.With reference to M.J.Heikkila, P.Komulainen and J.Lilleberg are entitled as " suppressing noise by adaptive channel equalizer in the CDMA down link ", the imagination channel value can estimate that the Griffith`s algorithm is used for the tap of self adaptation estimation balancing device by pilot frequency sequence.

In the system of a lot of use adaptive equalizers, training sequence periodically is sent to the adaptive equalization tap.In the mobile cellular environment, this is unpractical, if because channel variation is too fast and each user has the such expense of training sequence of oneself big too.For instance, use fertile assorted (Walsh-Hadamard) frequency expansion sequence in the single downlink channel in cdma system, on a channel, can provide orthogonal channel for reaching 64 users.For each user, a training sequence is periodically launched to adapt to the balanced chip that each customer mobile terminal receives, so that can receive described user's distinctive data.Because the information throughput of downlink channel is limited, so said method has greatly been saved the overhead of system.

Therefore, pressing for provides a kind of system and method, so that the multi-user can carry out the adaptive code chip equalization in the downlink channel in synchronous DS-CDMA system, and avoids being each user's transmitting training sequence in some sense.

In addition, pressing for provides a kind of system and method, to utilize the adaptive of an equalizer that always is present in a plurality of users that individualized training sequence in the data flow and this training can be used for synchronous DS-CDMA system continuously.

In view of the above, one object of the present invention is to provide a service, and the multi-user can carry out the adaptive code chip equalization in the downlink channel in synchronous DS-CDMA system to impel, and avoids being each user's transmitting training sequence in some sense.

Another object of the present invention is to provide a kind of system and method, to utilize the adaptive of an equalizer that always is present in a plurality of users that individualized training sequence in the data flow and this training can be used for synchronous DS-CDMA system continuously.

In an embodiment of the present invention, single training sequence comprises the pilot frequency sequence of a transmission, and described pilot frequency sequence is the synchronous and channel estimating that is used at the mobile receiver of most synchronous DS-CDMA systems at first, such as the down link of IS-95 and UMTS.Therefore, according to first aspect of the present invention, for a chip equalizer, one or more pilot frequency sequences are as training sequence, described training sequence always is present in the data flow, and this training can be used to continuously cell phone receiver the adaptation processing of equalizer.Especially, produced described method, promptly used these pilot frequency sequences adapting to the tap of a chip equalizer, and be the method that adopts spread user data before.With the tap that pilot frequency sequence comes adaptive chip equalizer, wherein carry out adaptive with symbol rate.

According to another aspect of the present invention, at ambulatory handheld receiver place, described a large amount of pilot frequency sequence, each all has a known chip to produce and send to carry out continuous equalizer adaptation.The a large amount of pilot tone that receives is with the higher adaptation rate of realization, and different IA High Speed Channel is followed the tracks of in realization expeditiously.In addition, invention comprises a least square algorithm so that be implemented in adaptive fast in the channel of quick decline when using many pilot frequency sequences.

Advantageously, receiver no longer need be about other user's the relevant sequence and the information of power; It is known that pilot frequency sequence that sends on the synchronous DS-CDMA system downlink channel and transmit power levels all are envisioned for for all users.

Below in conjunction with accompanying drawing the present invention is done detailed explanation, wherein:

Figure 1 shows that one of N the user's of DS-CDMA downlink channel of the present invention transmission and receiver module 10;

Figure 2 shows that a mathematic(al) representation e` _kAnd e _k, come relatively in a typical transmission system, to use RAKE receiver and the performance of using chip equalizer especially theoretically;

Figure 3 shows that the same expression formula of system shown in Figure 2, wherein pilot power is 20% of total transmitted power;

Figure 4 shows that the same expression formula of system shown in Figure 2, replace all users and use identical power, and select two users, make its transmitted power differ 20dB;

Figure 5 shows that the performance of the least square estimation device on the rayleigh fading channel of a 5-tap under the situation about moving with 60 kilometers speed of speed per hour.

Figure 1 shows that one of N the user's of DS-CDMA downlink channel of the present invention transmission and receiver module 10.Wherein, data a _k(i) symbols streams of expression user k will be sent by transceiver at 20 places in the base station, for example, receive by downlink channel 25 and the receiver member 30 that is moved in the hand-held set.Being similar to aforesaid reference according to foundation shown in Figure 1 structure 20 of the present invention is K.Hooli, M.Latva-aho, be entitled as " multiple access of the linear chip equalization device in the WCDMA descending link receiver disturbs and suppresses " with M.Juntti, P.Komulainen, M.J.Heikkila and J.Lolleberg, " adaptive channel equalizer of CDMA down link and interference suppress ", or the like.Suppose that described quantity all is real, and then obviously be to extend to complex types.

For achieving the above object, the transmitting system of module 10 is envisioned for synchronous DS-CDMA.Sequence spreading is envisioned for the quadrature white noise.Above-mentioned requirements may reach, such as, be the Walsh-Hadamard sequence string of " N " by using long, and described each sequence by length the PN sequence scrambling of " N ".Though result herein is to develop the scrambling of short PN sequence, the Simulation result of long PN sequence scrambling has demonstrated same performance.If Tc is the chip spacing, and T is a character spacing.Tc=NT then, wherein N is the length of sequence spreading, simultaneously the maximum number of user that also can hold for system.

With reference to Fig. 1, and content described below is with reference to the content of back, and the content in a following footnote representative of consumer index, bracket is represented time index, and therefore, the waveform of user k can be used s _k(t) represent:

$s_k\left(t\right)=\sqrt{P_k}\underset{i=0}{\overset{\mathrm{Ns}-1}{\mathrm{\Σ}}}{a}_k\left(i\right)c_k(t-\mathrm{iT})---\left(1\right)$

N wherein _sBe the number of the symbol that sends, a _k(i) be the symbols streams of user k, Pk is the power of user k, c _k(t) be the spread-spectrum signal of user k, be expressed as:

$c_k\left(t\right)=\underset{n=0}{\overset{N-1}{\mathrm{\Σ}}}{c}_k\left(n\right)\mathrm{\Π}(t-n{T}_c)---\left(2\right)$

Wherein ∏ (t) be one (0, rectangular pulse Tc) and [c _k(0) c _k(1) ... c _k(N-1)] be the frequency expansion sequence of user k.According to the present invention,, imagine a user a as what be described in more detail below ₀(i), comprise a pilot signal 15, comprise that corresponding sequence spreading 17 is expressed as c ₀(t). by above-mentioned description, be expressed as to the transmission signal d (t) 22 of all N user's combination a branch user:

$d\left(t\right)=\underset{k=0}{\overset{N-1}{\mathrm{\Σ}}}{s}_k\left(t\right)=\underset{k=0}{\overset{N-1}{\mathrm{\Σ}}}\sqrt{p_k}\underset{i=0}{\overset{N_s-1}{\mathrm{\Σ}}}{a}_k\left(i\right)\underset{n=0}{\overset{N-1}{\mathrm{\Σ}}}{c}_k\left(n\right)\mathrm{\Π}(t-\mathrm{iT}-n{T}_c)---\left(3\right)$

As shown in Figure 1, all users' transmission signal is expressed as h (t) by the multipath channel 25 with sample, and affix noise 27 is received machine 30 and receives.The baseband signal 29 that receives, i.e. r (k) is expressed as synchronously and after with spreading rate Tc sampling in last back:

$r\left(k\right)=\underset{i=0}{\overset{L_h-1}{\mathrm{\Σ}}}h\left(i\right)d(k-i)+n\left(k\right)---\left(4\right)$

L wherein _hBe the length of multipath channel, n (k) has mixed additive white Gaussian noise and equal zero-sum deviations _n ²Send sequence d (l) with sampling:

$d\left(l\right)=d\left({\mathrm{lT}}_c\right)=\underset{k=0}{\overset{N-1}{\mathrm{\Σ}}}\sqrt{p_k}\underset{i=0}{\overset{N_s-1}{\mathrm{\Σ}}}{a}_k\left(i\right)\underset{n=0}{\overset{N-1}{\mathrm{\Σ}}}{c}_k\left(n\right)\mathrm{\Π}\left(\right)l-n-\mathrm{iN})T_c---\left(5\right)$

The Minimum Mean Square Error receiver

As shown in Figure 1, received signal r (k) is at first sampled with spreading rate, is L by length then _fAdaptive line chip equalizer f40 handles.Equalizer runs on all received signals, and described received signal comprises all users that all comprise pilot tone 15, in order to express purpose intuitively, as user a ₀(k).In output place of equalizer, the user data sequence of expectation is by the described sequence spreading of despreading.And then, the output of equalizer, Be expressed as:

$\tilde{d}\left(k\right)=\underset{i=0}{\overset{L_f-1}{\mathrm{\Σ}}}f\left(i\right)r(k+d_f-i)---\left(6\right)$

D wherein _fIt is delay by equalizer 40.K ^ThData sequence 55 is by Solution Expander 60 despreadings:

${\tilde{a}}_k\left(m\right)=\underset{i=0}{\overset{N-1}{\mathrm{\Σ}}}\tilde{d}(\mathrm{mN}+i)c_k\left(i\right)---\left(7\right)$

All scaling imaginations are included in the tap f of equalizer.User k ^ThThe lowest mean square equalizer tap is confirmed as minimized mean square deviation E[| α _k(m)-α _k(m) |].This has expressed the MMSE tap f of user k apparently _k:

f _k＝H _k ^-1 y _k (8)

Matrix H wherein _kProvide according to equation (9):

$H_k(i,j)=\underset{p=0}{\overset{N-1}{\mathrm{\Σ}}}\underset{n=0}{\overset{N-1}{\mathrm{\Σ}}}{c}_k\left(p\right)c_k\left(n\right)E\left[r(\mathrm{mN}+p+d_f-i)r(\mathrm{mN}+n+d_f-j)\right],i.j=\mathrm{0,1}..L_f-1---\left(9\right)$

Y wherein _kFor:

y _k(i)∑c _k(p)E[α _k(m)r(mN+p+d _f-i)]，i＝0，1，...L _f-1 (10)

The Minimum Mean Square Error of above-mentioned tap is expressed as e _k=1- f _k ^T y _k, usually, f _kSeparate function for k, be different such as the tap of each user's the best, and according to sequence spreading.

The analysis of many MMSE equatioies about certain user is arranged and with respect to by the enhancing of RAKE receiver on performance here.According to the present invention, when physical channel 25, that is, h (t) is the same to all users, has reason to think to have a series of equalizer tap, and this is the best or approaching best for all users.So according to the present invention, equalizer tap f ₀Derivation is for Any user, and pilot frequency sequence approaches equalizer tap according to the scale vector, and which will be described below.As shown in Figure 1, do not have common decay, and hypothesis pilot tone sequence spreading is c ₀(n) 17, and the MMSE tap of pilot frequency sequence is f ₀Suppose to be used to k ^ThUser's equalizer tap f _k`=g <sub>k</sub> f <sub>0</sub>Be used for replacing the MMSE tap f <sub>k</sub>, when f <sub>k</sub>` is during as an equalizer 40, g _kIt is a gain 63 that minimizes mean square deviation.Thereby derive g easily _k=( f ₀ ^TH _k f ₀) f ₀ ^T y _kAnd use f _k` replaces f <sub>k</sub>Mean square deviation MSE be expressed as e` _k=g _k ² f ₀ ^TH _k f ₀-2g _k f ₀ ^T y _k+ 1.

Figure 2 shows that e _kAnd e` <sub>k</sub>Mathematical simulation, especially, in transmission system, using RAKE receiver or using chip equalizer to do a theoretic comparison at aspect of performance.The transmission parameter that uses is: N=64, L <sub>f</sub>=10, d <sub>f</sub>=4, the chip signal to noise ratio snr=-5dB.System uses equal transmitted power and pilot frequency sequence for all users and at full capacity.The binary Walsh-Hadamard sequence and the BPSK data [+1 ,-1] that are provided with the scrambling of short PN sequence are used together.The fixed channel h=[1.0 0.9 of one two ray] can be used for demonstrating.This is a typical channel, and RAKE receiver is moved very poorly, transmits an average output signal-to-noise ratio that is approximately 4.5dB, shown in curve 68.Output signal-to-noise ratio is by the symbol signal to noise ratio after balanced and the de-spread, that is, and and 10log (1/e <sub>k</sub>), work as equalizer f <sub>k</sub>Be used for user K, shown in the curve among Fig. 2 70.Output signal-to-noise ratio is by the symbol signal to noise ratio after balanced and the de-spread, that is, and and 10log (1/e` _k), work as equalizer f _k` is used for user K, shown in the dotted line among Fig. 2 75.Fig. 2 has expressed the equalizer that utilizes prior art, promptly send under the situation that training sequence carries out adaptive equalizer, output signal-to-noise ratio 70 after equilibrium and the despreading, and utilize pilot frequency sequence to carry out under the situation of adaptive chip equalizer, output signal-to-noise ratio 75 after equilibrium and the despreading, both almost are the same, and promptly all user's mean values are about 8dB, and above-mentioned ratio has improved 3.5BdB by the output signal-to-noise ratio 68 of RAKE receiver on performance.

Figure 3 shows that the same evaluation for system shown in Figure 2, wherein pilot tone accounts for 20% of total transmitted power.Therefrom visible and output signal-to-noise ratio 70,75 corresponding output signal-to-noise ratio 70` shown in Figure 2, the difference between the 75`, the signal to noise ratio snr s70 of this difference and system shown in Figure 2,75 compare greater.Its average output signal-to-noise ratio SNR is than low 0.8dB shown in Figure 2.This is that when the pilot power increase, then other users' transmission gross power reduces because of under the identical situation of gross power.

With reference to shown in Figure 3, result described herein represents, if it is adaptive to use chip equalizer that pilot tone is carried out in receiver, then sending pilot tone with high power is not to be that optimal design is necessary.In traditional DS-CDMA system, all be to send pilot tone, so that RAKE receiver is estimated channel with higher power.With reference to P.Komulainen, M.J.Heikkil  and J.Lilleberg are entitled as " adaptive channel equalizer of CDMA down link and disturb suppress ", supposes that channel parameter is known in chip equalizer adaptive, and wherein pilot tone is with higher power transmission.According to the present invention, directly adaptive on pilot frequency sequence when chip equalizer, then channel is without direct estimation, and then pilot power need not increase with respect to other users.This shows that more transmitted power can be used for user data.

Figure 4 shows that same evaluation, be different from all users and use identical power, but select the user that two transmitted powers differ 20dB for system shown in Figure 2.Such as, the first user P ₂₀=25 and the second user P ₅₈=25.All other users comprise pilot tone setting P _k=1.Then because all users have provided unacceptable result 68 in lower power RAKE receiver, but the output signal-to-noise ratio SNR75`` that is based on the equalizer of pilot tone is in close proximity to best equalizer output signal-to-noise ratio 70`` equally.Above-mentioned knot is tabled look-up bright, and it is possible carrying out on pilot frequency sequence with chip equalizer in the adaptive system down link is carried out power control at one on a large scale at one.

Least square with many pilot tones solves scheme

According to the second embodiment of the present invention, the equalizing device 40 of receiver as shown in Figure 1, with have only one to have the pilot tone of higher-wattage different, if i.e. 5 pilot tones and respectively account for 1/5 power or 10 pilot tones and respectively account for 1/10 power of a plurality of pilot tones are arranged, then be more conducive to follow the tracks of downlink channel.Therefore, each user will utilize several pilot frequency sequences, and promptly 5 or 10, no matter perhaps certain what pilot tone number that has been used for system comes adaptive equalizer.Advantageously, equalizer adaptation gets faster, because in each adaptation step, has the mistake corresponding to number of pilot sequences, and promptly 5 or 10, this can reduce and in order to quicken the adaptation speed of equalizer.Its result is that with respect to only with a pilot tone, mobile handset can move with higher speed and can keep better transmission performance.

Imagining one has identical transmitted power DS-CDMA system on all sequence spreadings, and the N of N sequence spreading _pFor known pilot frequency sequence is preserved.Do not have common decay, described sequence can be numbered 0 to N _p-1.Therefore, during each receiving symbol, N is arranged _pIndividual known symbol.Fast Channel estimates it is very important in the environment of the Rayleigh fading of the multipath that Doppler effect is arranged.Setting is used to estimate that the receiving symbol number of channel is Ns.Then user k has N _pNs known symbol is used on the time interval of Ns symbol estimates L _fEqualizer tap.Pass through N _pThe equalizer tap that pilot frequency sequence produces is used for balanced and de-spread k ^ThThe user.This passes through at all N _pCarrying out the LMS algorithm on the pilot tone simultaneously realizes.Least square solves scheme and can followingly carry out:

If a _Np=[a ₀(0) ... a _Np-1(0) a ₀(1) ... a _Np-1(1) a ₀(N _s-1) ... a _Np-1(N _s-1)] ^TVector for known pilot symbol transmitted.Then can get following matrix equality from equation (6) and (7):

CR f _Np＝ a _Np

Wherein R (i, j)=r (i+d _f-j) i=0 ... NN _s, j=0 ... L _f-1 and C be (a N _sN _p* NN _s) matrix comprises following pilot tone sequence spreading:

Therefore, f _NpLeast square solution scheme be f _Np=(X ^TX) ^-1X ^T a _NpX=CR wherein.This least square estimation is based on independent frequency pilot sign.In any case user K can come balanced and its data of demodulation with this identical equalizer vector.

Must understand that solve scheme except using least square, other technology also can be with solving equalizer tap f _Np, comprising the Kalman technology.

Shown in Figure 5 under actual conditions the tracking performance of above-mentioned algorithm.The system parameters of using in this example and aforesaid according to the system parameters that gathers way that is used for calculating channel shown in Figure 2 except L _f=20 and d _fBeyond=8 is identical.Described channel is that a 5-ray chip space rayleigh fading channel and mobile speed per hour are 60 kilometers.Described analog result realizes by on average being higher than 1000 different channels.f _NpEstimate to be used for remaining user of demodulation by least square algorithm described here.The one N _pSequence is a pilot tone.Just as expected, the number of the pilot frequency sequence in the system is big more, and then all users' performance is good more.For instance, as shown in Figure 5, system carries out 12 pilot frequency sequences, shown in curve 80, will get well in 78,79 the performance that improves aspect the SNR with respect to using less pilot frequency sequence.This is a loss to digital subscriber.Substitute to use a pilot frequency sequence that takies 20% power, uses a plurality of pilot frequency sequences that take 20% power more favourable aspect the tracking visual field.Under same total transmission pilot power, increased usertracking abilities all in the system.For the loss of data user's the sequence aspect that can get in a large number is owing to the user who is supported has been increased SNR cause, and can find out significantly from Fig. 5.Under the situation that 12 pilot frequency sequences are arranged, it also is possible that mobile speed per hour is higher than 100 kilometers.

Therefore, for all users, the performance and the best MMSE equalizer that fit in the chip equalizer on the pilot frequency sequence are very approaching.And the quantity that increases pilot frequency sequence aspect the channel variation fast is more more favourable than the power that increases single pilot tone following the tracks of.Use many pilot tones track channel change of transferring closely similar among this and the OFDM.At this, many frequency expansion sequences are served identical purpose.Difference is, in OFDM, each pilot tones is specific to a frequency, plug hole must be determined the frequency response of entire spectrum between tone, otherwise, in having many pilot tones preface DS-CDMA system more, if each sequence has a frequency response on the entire spectrum span, then needn't plug hole, the tap of equalizer just can be passed through LMS at an easy rate, and Kalman or least square algorithm are determined.

Because the present invention is described in conjunction with the embodiments, but be not limited only to the scope of aforesaid certain mode, on the contrary, be intended to cover and describedly select one, modification and form that be equal to comprises within the spirit and scope of the present invention, as what define in the dependent claims.

Claims (16)

1. in a direct sequence CDMA communication system (DS-CDMA) (10), transmit the method for information symbol, described system comprises that a base station (20) is used for going up at a channel (25) simultaneously transmitting the many information symbols signal (22) that is included as a plurality of mobile subscriber's appointments, and have channel response, described method comprises:

A) generation pilot frequency sequence (15) is used for the communication between synchronous described base station and the mobile subscriber, and goes up the described pilot signal of transmission at described individual channel (25) together with described signal, to be received by described a plurality of mobile subscriber's receiving systems (30);

B) adaptive chip equalizers of each user receiving device (30) configuration (40) to be following the tracks of described channel response,

C) at pilot signal (15) the adaptive described adaptive chip equalizers one or more equalizer taps of each described receiving system (30) with described reception, the described adaptive mistake that reduces the reception information symbol that is used to minimize;

D) with one and the described signal of the corresponding chip sequence of mobile subscriber (60) de-spread, from individual channel, to extract described user's information symbol.

2. the method for the described transmission information symbol of claim 1, the power that wherein transmits pilot signal is identical with the power that is sent to each information of mobile user symbol sebolic addressing, and/or wherein when the power increase of pilot signal transmitted, the power that then transmits each mobile subscriber reduces identical total transmitted power.

3. the method for the described transmission information symbol of claim 1, wherein comprise and produce a large amount of pilot frequency sequences (15) in step a), each has known chip sequence (17), and go up at an individual channel (25) simultaneously with described signal and to send described a large amount of pilot signal, described step c) comprises the one or more equalizer taps with the described chip equalizer of pilot signal self adaptation (40) of described each reception, described adaptive chip equalizers carries out adaptive based on a large amount of pilot signals (15) that receive, with carry out adaptive comparing based on a single pilot signal (15), at described adaptation step c) can carry out at faster speed adaptive, thus, described a large amount of pilot tone can be followed the tracks of fast-changing channel effectively.

4. the method for the described transmission information symbol of claim 1, wherein said pilot signal (15) are to send continuously, and described method makes that equalizer can be adaptive continuously.

5. a direct sequence CDMA (DS-CDMA) communication system comprises:

Base station (20) is used for comprising the signal of the many information symbols that are assigned to a plurality of mobile subscribers having on the individual channel of channel response (25) to transmit simultaneously, and has channel response.

Produce the device of pilot frequency sequence, described pilot frequency sequence has known chip sequence (17) and send described pilot signal (15) together with described signal on individual channel, and is received by described a plurality of mobile subscriber's receiving systems (30);

Adaptive chip equalizers (40) is configured in each user's receiving system place, to follow the tracks of described channel response;

Locate to use one or more equalizer taps of the adaptive described adaptive chip equalizers of pilot signal (15) that receives at each user receiving device (30), described adaptive minimizing receives the mistake of information symbol, wherein said receiver is used and the described signal of the corresponding chip sequence of mobile subscriber (60) de-spread, to extract described user's information symbol from individual channel (25).

6. the described DS-CDMA of claim 5 system, the power that wherein transmits pilot signal is identical with the power that is sent to each information of mobile user symbol sebolic addressing, and/or wherein when the power increase of pilot signal transmitted, the power that then sends each user reduces identical total transmitted power.

7. the described DS-CDMA of claim 5 system, wherein said base station (20) comprises that device is used to produce the pilot frequency sequence (15) that a large amount of each includes known chip sequence (17), and go up a large amount of pilot signal of transmission at individual channel (25) simultaneously, described device is used for carrying out adaptive with the pilot signal of described each reception to one or more equalizer taps of described chip equalizer, described adaptive chip equalizers carries out adaptive based on a large amount of pilot signals that receive, with carry out adaptive comparing based on a single pilot signal, can carry out adaptive at faster speed at described self-reacting device, thus, described a large amount of pilot tone might be followed the tracks of fast-changing channel effectively.

8. DS-CDMA as claimed in claim 5 system, wherein said pilot signal (15) send continuously, and described device makes that equalizer can be adaptive continuously.

9. the method for the chip equalizer (40) of receiving symbol in the channel (25) that fits in quick decline, described method comprises:

A) produce a large amount of pilot frequency sequences (15), each has known chip sequence (17);

B) go up described a large amount of pilot signal of transmission and the signal that comprises many information symbols at individual channel (25) simultaneously, many information symbols comprise the data sequence that is assigned to a plurality of mobile subscribers (30);

C) at each user's receiving system place configuration adaptive chip equalizers (40) following the tracks of described channel response, and provide equalizer output (50) to be used for despreading to think that certain user provides a data sequence;

D) at pilot signal (29) adaptive described adaptive chip equalizers (40) the one or more equalizer taps of described each receiving system (30) with described reception, the described adaptive mistake that receives information symbol that is used to reduce;

E) with one and the described signal of the corresponding chip sequence de-spread of mobile subscriber (60) (50), from individual channel (25), to extract described user's information symbol, wherein said adaptation step d) comprise that using a least squares approach comprises step:

Produce the vector of known transmission pilot frequency information symbol a _Np

Produce the matrix c of a pilot tone frequency expansion sequence;

Estimate described equalizer tap according to following formula f _Np: ${\underset{\&OverBar;}{f}}_{N_p}={\left(X^{T}X\right)}^{-1}{X}^T{\underset{\&OverBar;}{a}}_{N_p}$ X=CR wherein

Wherein R (i, j)=r (i+d _f-j) i=0 ... NN _s, j=0 ... L _f-1, N wherein _sThe number of the receiving symbol when being used to estimate channel response, L _fSum for equalizer tap.

10. device is used for simultaneously sending signal of communication on a channel with channel response, and described signal of communication comprises the many information symbols that are assigned to a plurality of users, and described device comprises:

Generation has the pilot frequency sequence device of chip sequence;

A conveyer, on individual channel, send described signal of communication and described pilot signal, and received by described a plurality of mobile subscriber's receiving systems, described receiving system comprises that an adaptive chip equalizers is to follow the tracks of described channel response, and with one or more equalizer taps of the adaptive described adaptive chip equalizers of pilot signal that receives, the mistake of described adaptive minimizing receiving symbol;

Wherein said receiving system is with one and the described signal of the corresponding chip sequence de-spread of mobile subscriber, to extract described user's information symbol from individual channel.

11. the device described in the claim 10, the power that wherein transmits pilot signal is identical with the power that is sent to each information of mobile user symbol sebolic addressing, and/or wherein when the power increase of pilot signal transmitted, the power that then sends each user reduces identical total transmitted power.

12. the device described in the claim 10, the device that wherein produces pilot frequency sequence also produces the pilot frequency sequence that a large amount of each includes known chip sequence, and the while sends a large amount of pilot signals on individual channel, described device is used for carrying out adaptive with the pilot signal of described each reception to one or more equalizer taps of described chip equalizer, described adaptive chip equalizers carries out adaptive based on a large amount of pilot signals that receive, with carry out adaptive comparing based on a single pilot signal, can carry out adaptive at faster speed at described self-reacting device, thus, described a large amount of pilot tone can be followed the tracks of fast-changing channel effectively.

13. the device described in the claim 10, wherein said pilot signal are to send continuously, described device makes that equalizer can be adaptive continuously.

14. the receiver of a communication system, described reception function receiving communication signal, described signal of communication transmits on a channel with channel response simultaneously, described signal of communication comprises the many information symbols that are assigned to a plurality of mobile subscribers, described signal of communication comprises that each includes the pilot signal of known chip sequence, and described receiver comprises:

Adaptive chip equalizers is used for receiving described signal of communication and pilot signal simultaneously, and an equalizer output is provided;

Be used for the described equalizer output of de-spread and think that certain user provides the device of a data sequence;

One or more equalizer taps of wherein said adaptive chip equalizers come adaptive with described reception pilot signal, described despreading device is used and the described signal of communication of the corresponding chip sequence de-spread of mobile subscriber, to extract described user's information symbol from individual channel.

15. the receiver described in the claim 14, wherein said signal of communication comprises that a large amount of each includes the pilot frequency sequence of known chip sequence, and the while sends a large amount of pilot signals on an individual channel, described adaptive chip equalizers carries out adaptive with the pilot signal that receives to one or more equalizer taps of described chip equalizer, described adaptive chip equalizers carries out adaptive based on a large amount of pilot signals that receive, with carry out adaptive comparing based on a single pilot signal, can carry out adaptive at faster speed at described adaptive chip equalizers, thus, described a large amount of pilot tone can be followed the tracks of fast-changing channel effectively.

16. the described receiver of claim 14, wherein said pilot signal are to send continuously, described device makes that equalizer can be adaptive continuously.

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