WO2002049301A1 - A channel estimating method - Google Patents

A channel estimating method Download PDF

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Publication number
WO2002049301A1
WO2002049301A1 PCT/CN2000/000576 CN0000576W WO0249301A1 WO 2002049301 A1 WO2002049301 A1 WO 2002049301A1 CN 0000576 W CN0000576 W CN 0000576W WO 0249301 A1 WO0249301 A1 WO 0249301A1
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WO
WIPO (PCT)
Prior art keywords
pilot symbols
different
interference
channel estimation
pilot
Prior art date
Application number
PCT/CN2000/000576
Other languages
French (fr)
Chinese (zh)
Inventor
Michael Li
Original Assignee
Linkair Communications, Inc.
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Linkair Communications, Inc. filed Critical Linkair Communications, Inc.
Priority to PCT/CN2000/000576 priority Critical patent/WO2002049301A1/en
Publication of WO2002049301A1 publication Critical patent/WO2002049301A1/en

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Classifications

    • HELECTRICITY
    • H04ELECTRIC COMMUNICATION TECHNIQUE
    • H04LTRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L25/00Baseband systems
    • H04L25/02Details ; Arrangements for supplying electrical power along data transmission lines
    • H04L25/0202Channel estimation
    • H04L25/0224Channel estimation using sounding signals
    • H04L25/0228Channel estimation using sounding signals with direct estimation from sounding signals

Abstract

The present invention discloses a channel estimating method using in the cellular mobile communication system, which transmits different pilot symbols having the correlation in both interference and fading in the same subframe at the transmitter side, at the receiver side, performs the difference operation on the received adjacent different pilot symbols, so as to eliminate interference and obtain the exact channel estimating value. The channel estimating method provided by the present invention can effectively eliminate the affect of the interference, give accurate channel parameter estimating value, avoid complex multi-users detection and reduce the complexity of the system.

Description

The channel estimation method

FIELD

The present invention relates to cellular mobile communication system, and particularly relates to an efficient channel estimation method that reduces or eliminates a cellular mobile communication system interference. BACKGROUND OF THE INVENTION

In modern cellular mobile communication, in order to eliminate the effects of the channel transmission characteristics of the transmission channel fading and the like, more accurately receive user traffic data, channel estimation techniques usually used. For example, Qualcomm (Qualcomm) is proposed in the third generation mobile communication standard IS-2000 consecutive pilot channel estimation, European Nokia, continuous pilot Errisson forth in WCDMA pilot joint channel and dedicated pilot channel estimating (Qualcomm continual pilot frequencies refer to specific embodiments Physical Layer Standard for ANSI / TIA / EIA- 95- B; WCDMA pilot in the joint channel estimation scheme can be found 3GPPTS25.211). Since the estimated channel estimation with interference methods are, therefore multiuser detection must be carried out, otherwise it will not give an accurate channel estimation result, thereby affecting the performance of communication systems. However, in large multi-user detection has greatly increased the complexity of the system. SUMMARY

Channel estimation method applied to a cellular mobile communication system proposed by the present invention, the multi-cell cellular environment, without affecting the use of multi-user detection conditions, can still be effectively eliminate the interference, give accurate channel estimation result .

A channel estimation method of the present invention, is in the same sub different frames transmitted pilot symbol transmission side, the interference between pilot symbols of the different correlated fading also has relevance; the following steps at the receiving end: (a ) are different on the received pilot symbols despread in-phase demodulation, and despreading parallel conversion, quadrature demodulation and serial-parallel converter;

(B) are adjacent after the serial to parallel conversion of different pilot symbols subtraction operation to eliminate the interference, and the calculation result of the subtraction are averaged in order to further eliminate interference computation;

(C) the calculated dividing the result obtained in step b to obtain a channel phase offset estimation value; calculating the result of step b, and squaring to obtain the estimated fading value of the channel amplitude.

According to the above-described present invention, according to different leads of K pilot symbols may be different pilot symbols as a set, 2N transmit a pilot 2N / K group of pilot symbols, wherein K, v are positive integers.

When Κ 2, when transferring the group Ν 2Ν total pilot symbols, said step (b) is different adjacent the pilot frequency symbol string and conversion means the subtraction operation is calculated odd bit and the adjacent pilot symbols the difference between the pilot symbol even bit pilot.

When K is 2N, 2N transmit a different set of co-pilot symbols, according to step b of guiding the pair of adjacent parallel conversion pilot symbol subtraction operation means calculates the first pilot symbol with the M-bit the first M - 1 frequency difference between the position pilot symbols, wherein M is less than or equal to the positive even number 2N.

It was Gen aspect of the present invention, the different pilot symbols may also be of the same pilot symbol is a group consisting of K, total conductivity of 2N different transmission 2N / K group of pilot symbols, wherein, N We are positive integers.

When K is 2, when a total of N sets of different transmission 2N pilot symbols, performs the step (b) a subtraction operation means different pair of adjacent pilot symbols after the serial-parallel conversion of an odd bit calculation adjacent pilot the difference between the adjacent symbols and the pilot difference value between the even bit symbol frequency.

When K is N, when transmitting two different sets of 2N total pilot symbols in the step ¾ 13 different pair of adjacent pilot symbols after the serial-parallel conversion means for computing subtraction operation of pilot bits M the difference between the pilot symbol bits of the symbol and the second (N + M), where M is less than or equal to N is a positive integer.

Different from the above pilot symbols, whichever best correlation characteristic value is the minimum.

According to an estimation apparatus is applied to a cellular communication system according to the present invention provides a method of channel, comprising in-phase demodulation despreading means despreads the quadrature demodulator, serial to parallel converter, a subtractor, a sharing device, a divider and a square and a calculator. Wherein the despread received signals in phase quadrature demodulator demodulating the despreading means despreads demodulating means; signal after despreading are demodulated respectively by the serial-parallel converter and converted string; respectively subtractor different adjacent pilot symbols after the serial-parallel conversion operation performed to eliminate the interference difference; the difference computation results of further accumulated averaged to eliminate interference by the averager, respectively; the average output of the divider is carried out in the division, in order to obtain a phase shift channel estimates; averager output is squared and the square-sum operation of the operator, to obtain a channel fading amplitude estimate.

Pilot symbol channel estimation method of the present invention, in the transmitting side transmission interference and fading has a different forms of relevance in the arithmetic receiving end through different forms of the derivative of the adjacent pilot symbols to remove interference, a multi-cell under interference, multiuser detection is not used, still can effectively eliminate the influence of interference given green ^ correct channel parameter estimation information, reducing the complexity of the system. BRIEF DESCRIPTION OF DRAWINGS

Figure 1 is a wireless communication system substantially schematic block.

FIG 2 is a schematic view of a frame structure.

Figure 3 is a schematic view of examples of the present invention, four kinds of pilot pilot symbol design embodiment.

FIG 4 is a schematic block diagram of apparatus in accordance with one channel estimation method of the present invention. Embodiment of the present invention.

Expressed by the following equation of the present invention is described in detail in conjunction with the accompanying drawings. 1, the k-th sampling time, the signal reception apparatus 105 receives the Refer to the accompanying drawings: r k = a k s k + I k + n k (1)

Where r t, ^, / A. , Respectively, in the k-th sampling timing, the received signal 105 of the receiving apparatus, the signaling device 101 transmits transmission, fading channel fading factor of 102, the interference signals from the same cell and other cells 106, 107, and a white noise signal.

Estimating channel parameters by a signal or pilot symbol, and the estimation results of the pilot symbols as reference symbols after the data, and the results of these estimates remain constant in one frame, then the frame structure of the system 2 with reference to the accompanying drawings.

The core process of the present invention is to achieve the design of a pilot structure. Traditional designs are pilot structure to transmit the same pilot symbols, while the present invention is different from pilot symbols transmitted in the same subframe, the term may refer to a different position on which different signal constellation, and the constellation the larger distance the better, when the correlation characteristics between two different pilot symbols for the best minimum value. The same subframe interference between different pilot symbols in the relevant area, also in the relevant region fading.

Referring to Figure 3, Figure 3 shows a structure of a pilot symbol of several designs of the present invention. Wherein, (A) and (b) a pilot symbol is shown by a plurality of sets of pilot symbols repeats, different from each other between the pilot symbols of each group. (A) it is shown by the two different pilot symbols, Ρ 2 form a group, the group consisting 2Ν Ν total pilot symbols. (B) shown by a group of 2N mutually different pilot symbols Ρ 7, Ρ 2, Ρ 3 , Ρ 4 "- · 'Ρ2Ν-ι, Ρ 2Ν composition herein should satisfy the condition that the value of N different. fading and interference between pilot symbols are relevant.

(C) and (d) shows the pilot symbols by a plurality of sets of pilot symbols, each of the same frequency are pilot symbols, the pilot symbols using different between the groups. (C) are respectively shown by the same two pilot symbols ^, P 2 and P 2, ····· · Ρ Ν -ι and P N - !, P N form a group of the PN, a total of 2N group consisting of N pilot symbols, P 2, ····· P N is the! ^ Mutually different pilot symbols. (D) shows the same is composed of N pilot symbols P 7 and A are composed of a group, the group consisting of a total of 2N 2 pilot symbols, and 2 are two different pilot symbols. Where the value of N should be satisfied that the interference and fading between different pilot symbols are relevant.

Take Figure 3- (a), for example, by deriving this transformation described pilot structure for channel estimation and brings great convenience effectively eliminate the interference.

Provided in a pilot symbol of a total of 2N, the odd-numbered pilot symbols are transmitted signal in the even-numbered pilot symbols transmitted signals A, i.e. the k-th pilot symbol is:

{(2)

among them:

Pi = cos (fi) t + 0) -Q k sinOt + 0) = A k cos (6¾ +. + ^) () P 2 = I k cos (ot + + sm (ot + φ 0) = Α! (cos (+ φ 0 ^ after channel fading, the additional interference fading and the white noise factor, the form of equation (1) of the received signal at this time is somewhat similar expressions are:

, J 'k cos (6) t + φ 0 + φ ά1ι + φ Ι [) + Ι Ιζ + n k k = l, 3, - ·, 2Ν-1 (Λ, r k = k p kd + I k + n k = <t ,, (4)

[a k cos (iyt + φ 0 + φ Λ - ^) + / / c + n k k = 2,4, '· ·, fading is introduced phase offset 2Ν formula.

Since the adjacent pilot shorter interval between symbols, and inter-symbol interference of the pilot having different correlated fading is also relevant, and thus between the adjacent pilot symbol has a k = a k . _ x, p dk = ( p d w, I k = I k _ x (k = l, 2, ···, N) Thus, the first 2k-l, 2k pilot symbols are:

r 2k = + N 2k (6) k = l, 2, ·· ', N

4 with reference to the drawings, at this time the receiving end receives a signal through despreading demodulation means 401 demodulates the in-phase complete, outputs the serial to parallel converter 403; despreading demodulation means after completion of the orthogonal demodulator 402, serial-parallel converter 404 outputs respectively signals obtained as follows:

(7) d (2k-l) o = + (24-1) + n 0 ( 2k-l) (8) diks = a 2k A 2k COSOQ + φ 21ί a φ ά2Ιί) + I s2k + n s2k (9) dike = ^ 2k A 2k sin (^ 0 + u- <Pd2 k) + I.u + n olk (10) k = l, 2, ···, N

405 used to perform arithmetic (7) - (9), are:

C h = -2α, Λ sin + φ &) sin () + n, sk k = l, 3, 5 ···, 2N- 1 (11) 406 used to perform arithmetic unit (8) - (10), Have:

C ks = 2a k A k cos (^ 0 + ^) sin (^) + n, ok k = l, 3, 5 ···, 2N-1 (12) where:

k = l, 3,5, 2N- 1 (13) k = n ok - κ = 1 '3, 5, ......, 2N-1 (14) n k, n k is zero-mean Gaussian white noise.

From (11), (12) is represented by the formula it can be seen, the noise has been substantially eliminated, precise signal energy estimate, but also to remove the effect of white noise. Requires (11), (12) taken for this average.

Sharing device 407, respectively 408 (11), (12) are averaged. Since there are 2N pilot symbols, by the above derivation process, after the sign of the inter-frequency adjacent guide subtraction operation, in

(11), (12) where only N terms, it is possible to (11), (12) N items taken Average: f sk (15) c ko = - Σ 2 ^ cos (^ 0 + φ ά (ί) sin (^,) + -Σ n k (16) through (15), (16) the average operation, largely eliminates noise effects, since the reception interference and P 2 and correlated fading transmission channel via substantially the same, therefore:

c fa = 2 k A k sin + ^) sin (^) + n (17) c ko = 2 k A k cosO 0 + ¾) sin (^) + n '0 (18) ^ a case, the averaged Having become very small.

By calculating the square sum calculator 409 (17) * (17) + (18) * (18) to give:

Since small values of the known pilot symbol signal, it is 4, sitin signal are known, while n "is, in this negligible, and therefore equation (19) divided by a constant term 4 sin 2 (^), it signal amplitude fading factor obtained estimate c k.

The divider 410 for performing arithmetic expressions (17) / (18), to give:

tg9 sp = tg + (20) Similarly, since the pilot symbol is a known signal, as known information, n "is negligible small value, so that we can obtain the estimate of the phase offset values ^.

Since the estimated channel parameters ^, ^ + It has been eliminated the influence of interference and noise to a large extent, the estimation accuracy of the estimated value is much higher than the presence of interference and noise of the prior art, thus a three effective channel estimation method. The present invention is a transmission interference and fading in the same subframe transmitting side of has a different pilot symbol correlation, the exact value at the receiving end by the different pilot symbols received operation to eliminate interference, to obtain channel estimation . Using the channel estimation method provided by the invention, can in the case of multi-cell multi-user interference, give accurate channel estimation value, and avoids complex multiuser detection, reducing the complexity of the system, it is a suitable cell effective channel of the mobile communication system or a communication interference estimation methods. Only the foregoing embodiments of the present invention a preferred embodiment will be described, the present invention is not intended to limit, in any any modifications within the spirit and principle of the present invention, made, equivalent substitutions, improvements, etc., should be included in the present invention. within the scope of the claims.

Claims

Claims
A channel estimation method applied to a cellular mobile communication system, characterized in that the method comprises:
In the same subframe transmitting side transmits different pilot symbols, the interference between the pilot symbols having different correlated fading also has relevance; the steps performed at the receiving end:
(A) for each different pilot symbols received despread and demodulated in-phase converter and the despreading sequence, and the serial-parallel conversion quadrature demodulator; other interference, and the calculated results are averaged subtraction operation to further eliminate interference;
(C) the calculated dividing the result obtained in step b to obtain a channel phase offset estimation value; calculating the result of step b, and squaring to obtain the estimated fading value of the channel amplitude.
2. The channel estimation method according to claim 1, wherein: said pilot symbols are different from the K different frequency means of a set of pilot symbols is transmitted
2N / 2N of guide Group K pilot symbols, wherein K, v are positive integers.
3, the channel estimation method according to claim 2, wherein: said Κ 2, Ν group were transferred 2Ν pilot symbols;
Adjacent the said serial to parallel conversion of different pilot symbols subtraction operation means calculating the difference between the odd bit pilot symbols adjacent pilot symbols even bit.
4, the channel estimation method as claimed in claim 2, UN, wherein: said Κ is 2v, 2v total transmit a different set of pilot symbols;
The different pair of adjacent pilot symbols after the serial-parallel conversion means for computing subtraction operation of the pilot bit [mu] [mu] symbol and - a difference between a pilot symbol, where [mu] is less than or equal 2Ν the positive even number.
5. The channel estimation method according to claim 1, wherein: said pilot symbols are different from the K refers to the same pilot symbols for a group, a total of 2N different transmission 2N / K group pilot symbols, wherein K, Ν are positive integers.
6, according to claim 5 wherein the channel estimation method, characterized in that: said Κ 2, different transmission Ν group 2Ν total pilot symbols;
Adjacent the said serial to parallel conversion of different pilot symbols subtraction operation is the difference between the adjacent guide difference between the even bit and odd bit calculating pilot symbols adjacent pilot symbols.
7. The channel estimation method according to claim 5, wherein: said Κ is v, a total of two sets of different transmission 2Ν pilot symbols;
Different said adjacent pilot symbols after the serial to parallel conversion subtraction operation is the difference between the calculated pilot symbols Zi [mu] bits and the second pilot symbols (Ν + Μ) bits, where [mu] is the Ν less than or equal to a positive integer.
8, a channel estimation method according to any one of claim 7, wherein: the best setting different pilot symbols for its relevant characteristics is smallest.
9. A cellular communication system is applied to a channel estimation apparatus, wherein: the apparatus comprises in-phase demodulation despreading means despreads the quadrature demodulator, serial to parallel converter, a subtractor, a sharing device, divider and square sum calculator;
Wherein the despread received signals in phase quadrature demodulator demodulating the despreading means despreads demodulating means; signal after despreading are demodulated respectively by the serial-parallel converter and converted string; respectively subtractor different adjacent pilot symbols after the serial-parallel conversion operation performed to eliminate the interference difference; the difference computation results of further accumulated averaged to eliminate interference by the averager, respectively; the average output of the divider is carried out in the division, in order to obtain a phase shift channel estimates; averager output is squared and the square-sum operation of the operator, to obtain a channel fading amplitude estimate.
PCT/CN2000/000576 2000-12-14 2000-12-14 A channel estimating method WO2002049301A1 (en)

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CNB008136033A CN1152537C (en) 2000-12-14 2000-12-14 Channel estimating method and apparatus
PCT/CN2000/000576 WO2002049301A1 (en) 2000-12-14 2000-12-14 A channel estimating method
AU2141301A AU2141301A (en) 2000-12-14 2000-12-14 A channel estimating method
HK03102926A HK1050783A1 (en) 2000-12-14 2003-04-24 A channel estimating method and equipment.

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Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN101505495A (en) * 2008-02-05 2009-08-12 夏普株式会社 Interference coordination method and base station for uplink FDM cellular communication system

Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN1253433A (en) * 1998-11-02 2000-05-17 日本电气株式会社 Channel characteristics inference device
WO2000060762A1 (en) * 1999-04-08 2000-10-12 Qualcomm Incorporated Channel estimation in a cdma wireless communication system
EP1047233A2 (en) * 1999-04-23 2000-10-25 Lucent Technologies Inc. Iterative channel estimation and compensation based theron

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN1253433A (en) * 1998-11-02 2000-05-17 日本电气株式会社 Channel characteristics inference device
WO2000060762A1 (en) * 1999-04-08 2000-10-12 Qualcomm Incorporated Channel estimation in a cdma wireless communication system
EP1047233A2 (en) * 1999-04-23 2000-10-25 Lucent Technologies Inc. Iterative channel estimation and compensation based theron

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN101505495A (en) * 2008-02-05 2009-08-12 夏普株式会社 Interference coordination method and base station for uplink FDM cellular communication system

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AU2141301A (en) 2002-06-24
HK1050783A1 (en) 2004-12-10
CN1385017A (en) 2002-12-11
CN1152537C (en) 2004-06-02

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