WO2002045447A1

WO2002045447A1 - A method for measuring signal to interference plus noise ratio

Info

Publication number: WO2002045447A1
Application number: PCT/CN2000/000526
Authority: WO
Inventors: Michael Li; Daoben Li
Original assignee: Linkair Communications, Inc.
Priority date: 2000-11-29
Filing date: 2000-11-29
Publication date: 2002-06-06
Also published as: CN1171489C; HK1050800A1; AU2001216906A1; CN1385043A

Abstract

The present invention disclosed a method for measuring SINR of cellular mobile communication system under any interference, including: transmitting the different pilot signs in the same subframe of the send end, there are correlation between the different pilot signs and interference and fading; in the receive end, operating the received different pilot signs to eliminate interference, so that obtain the measurement value of SINR. The method of present invention can eliminate the effect of interference, it can give the accurate SINR value under the multiple users interference.

Description

Method for measuring signal-to-interference ratio

Technical field

The present invention relates to the technical field of cellular mobile communications, and in particular, to a method for measuring a signal-to-interference and noise ratio (SINR). Background of the invention

In modern cellular mobile communications, the implementation of many algorithms, such as power control, adaptive modulation coding (AMC), and turbo coding, requires accurate estimation of the signal to interference and noise ratio SINR (Signal to Interference plus Noise Ratio). ). In order to obtain accurate SINR, many scholars have conducted a lot of theoretical research in this field. E.g:

① In an article by MD Austin and GL Stuber entitled "In service signal quality estimation for TDMA cellular systems" (in Proc. PIMRC, 1995, pp. 836-840), Austin and Stuber proposed a method using training sequences for For SINR estimation algorithm, if no training sequence is used, its estimation accuracy depends on the symbol error characteristics.

② An article by M. Andersin, N. B. Mandayam, and R. D. Yates is

In the article 'Subspace based estimation of the signal to interference ratio for TDMA cellular systems "(in Proc. VTC, Atlanta, GA, 1996, pp. 1155-1159), Andersin et al. Proposed another method, namely The characteristic roots of the signal variance matrix are decomposed to obtain the estimated value of SINR.

③ An article by M. Turkboylari and GL Stuber entitled "An efficient algorithm for estimating the signal-to-interference ratio in TDMA cellular systems" (IEEE Trans. Comrnun., Vol. 46, pp. 728-731, June 1998 Another new method proposed by Turkboylari and Stuber in the article is based on projecting the received signal Go to the subspace characterizing the desired signal to get an estimate of the SINR.

④ Recently, a novel SINR estimation method was proposed by Krishna Balachandran, Srinivas R. Kadaba and Sanjiv Nanda. This method is recorded in the topic entitled "Channel Quality Estimation and Rate Adaptation for Cellular Mobile Radio" (IEEE Trans. Commun., Vol. 17, pp 1244-1256), the SINR value is calculated by calculating the Euclidean distance between the decoded signal and the desired signal during the decoding process.

Looking at the above methods, it can be seen that the first three methods are too complicated and require a long training sequence. They are not suitable for fast power control and are difficult to apply in practical systems. Although the fourth method seems simple, the premise of applying this method is that the parameters of the signal must be accurately estimated. However, in a cellular communication system, due to the presence of multi-user and multi-cell interference, multi-user detection is required to accurately estimate the parameters of the signal, and this will greatly increase the complexity of the system.

A SINR measurement method proposed in WCDMA (see "Physical Layer Standard for WCDMA, 3GPP TS25. 211" for details) is to calculate the SINR measurement value by calculating the squared difference of the received signal. The application of this method must have An important premise is that the mean value of the perturbation is zero. In WCDMA and IS-2000, this is achieved by performing pseudo-code spreading on each cell, so the application of this method has great limitations. Summary of the Invention

The present invention provides a method for measuring a signal-to-interference and noise ratio (SINR) applied to a cellular mobile communication system. The method includes: transmitting different pilot symbols in a same subframe at a transmitting end, Interference has correlation, and fading also has correlation. At the receiving end, the SINR measurement value is obtained by computing the received different pilot symbols to eliminate interference. 2N / K groups of 2N pilot symbols are sent, where K and N are positive integers. In this way, when K is 2, two different pilot symbols of the N group are transmitted. When K is 2N, 2N different pilot symbols are transmitted for one group. A total of 2N pilot symbols of different 2N / K groups are transmitted, where K and N are both positive integers. In this way, when K is 2, a total of 2N pilot symbols are transmitted for transmitting different N groups. When K is N, different 2 groups of 2N pilot symbols are transmitted.

According to the foregoing technical solution of the present invention, the operation of receiving different pilot symbols on the receiving end to eliminate interference, and obtaining a SINR measurement value includes the following steps:

(a) performing despreading, in-phase demodulation, and serial-to-parallel conversion on the received different pilot symbols, and performing a subtraction operation on adjacent different pilot symbols after serial-to-parallel conversion to eliminate interference; at the same time, the different pilot symbols Performing despreading, orthogonal demodulation, and serial-to-parallel conversion, and performing subtraction operations on adjacent different pilot symbols after serial-to-parallel conversion to eliminate interference;

(b) averaging the subtraction calculation results in step a to further eliminate interference;

(c) square the sum of the calculation results in step b to obtain the signal energy;

(d) Calculate the total energy of the signal and subtract the energy of the signal in step c to obtain the total energy of interference and noise;

(e) Divide the signal energy by the total energy of interference and noise to get the SINR measurement. In the above step (a), when the different pilot symbols are composed of two different pilot symbols as a group, and N groups of 2N pilot symbols are transmitted in total, the pair-to-serial conversion is performed. Subtracting the adjacent different pilot symbols refers to calculating the difference between the pilot symbols of odd bits and the pilot symbols of adjacent even bits.

In the above step (a), when the different pilot symbols refer to transmitting 2N different pilot symbols, the subtraction operation is performed on adjacent different pilot symbols after serial-parallel conversion. Refers to calculating the difference between the M-th pilot symbol and the M-1-th pilot symbol, where M is a positive even number less than or equal to 2N.

In the above step (a), when the different pilot symbols are composed of two identical pilot symbols as a group, and different N groups of 2N pilot symbols are transmitted, the pair of strings Subtracting the adjacent different pilot symbols after conversion means calculating the difference between the odd-numbered adjacent pilot symbols and the even-numbered adjacent pilot symbols.

In the above step (a), when the different pilot symbols refer to a group consisting of N identical pilot symbols, and different 2 groups of 2N pilot symbols are transmitted, the pair of strings Subtracting the adjacent different pilot symbols after conversion means calculating the difference between the Mth pilot symbol and the (N + M) th pilot symbol, where M is less than or equal to N Positive integer.

The above-mentioned different pilot symbols are best to take their correlation characteristic values to the minimum.

A measuring device for a signal-to-interference and noise ratio (SINR) applied to a cellular communication system according to the method of the present invention includes a despread in-phase demodulation device, a despread quadrature demodulation device, a serial-to-parallel converter, and a subtractor. , An equalizer and an arithmetic unit, wherein the received signals are despread and demodulated by a despread in-phase demodulation device and a despread quadrature demodulation device respectively; and the despread and demodulated signals are each performed by a serial-parallel converter. Serial-to-parallel conversion; Subtracter performs differential operation on adjacent different pilot symbols after serial-to-parallel conversion to eliminate perturbation; Divide the difference operation results by averager to average and further eliminate interference; The device calculates the total energy, calculates the sum of squares of the operation results of the equalizer, thereby obtaining the signal energy, further obtains the total energy of interference and noise, and divides the signal energy by the total energy of interference and noise to obtain the SINR measurement.

The SINR measurement method proposed by the present invention can effectively remove the influence of interference, and give accurate SINR measurement values under arbitrary interference conditions. At the same time, complex multi-user detection is avoided, the algorithm is simple and easy to implement, and has great application value in practical engineering. Brief description of the drawings

Figure 1 is a basic schematic block diagram of a wireless communication system.

Figure 2 is a schematic diagram of a frame structure.

FIG. 3 is a schematic diagram of an implementation example of four pilot symbol designs according to the present invention.

Fig. 4 is a block diagram of a measuring device according to the method of the present invention. Mode of Carrying Out the Invention

The present invention is described in detail below through the expression of formulas in conjunction with the drawings. Referring to FIG. 1, at the k-th sampling time, the signal received by the receiving device 105 is: r _k = a _k s _k + I _k + n _k (1)

Where ^ ^, ^ Λ, respectively represent the signal received by the receiving device 105, the signal transmitted by the transmitting device 101, the fading factor of the fading channel 102, the interference signal 106 from the same cell and other cells at the kth sampling time, and White noise signal 107.

Pilot symbols are used to estimate SINR, signal, or channel parameters, and the estimation results of the pilot symbols are used as a reference for subsequent data symbols, and these estimation results remain unchanged within a frame. At this time, the frame structure of the system is referred to FIG. 2 .

The core of the method of the invention lies in the design of the pilot structure. The traditional pilot structure design all transmits the same pilot symbol, and the present invention transmits different pilot symbols in the same subframe. The so-called difference may refer to different positions on the signal constellation diagram, and the constellation diagram The larger the distance, the better. It is best when the correlation characteristic value between two different pilot symbols is the smallest. The interference between different pilot symbols in the same subframe is in the relevant area, and the fading is also in the relevant area.

Referring to FIG. 3, FIG. 3 shows structural designs of several pilot symbols of the present invention. The pilot symbols shown in (a) and (b) are composed of multiple sets of pilot symbols repeatedly, and the pilot symbols of each group are different from each other. (A) shows that it consists of two different pilot symbols, P ₂ Group, a total of N groups constitute 2N pilot symbols. (B) it is shown by a group of 2N mutually different pilot symbols _{_{[rho]], Ρ 2, Ρ 3, Ρ}} 4 '· → 2Ν - !, J¾v composition. Here, the value of N should satisfy the interference and fading between different pilot symbols.

The pilot symbols shown in (c) and (d) are composed of multiple groups of pilot symbols, each group is composed of the same pilot symbol, and different pilot symbols are used between groups. (C) shows two cadavers with the same pilot symbols respectively; and PN ₂ with a corpse ₂ , · — · 'PN- ^ P _N P _N ) P _N , and a total of N groups constitute 2N pilot symbols , P], P ₂ ,, ...: and are N pilot symbols different from each other. (D) shows a group consisting of N identical pilot symbols and / ^ respectively, a total of 2 groups constituting 2N pilot symbols, and P / and P ₂ are two different pilot symbols. Here, the value of N should also satisfy the interference and fading between different pilot symbols.

The following uses Figure 3-(a) as an example to explain the great convenience brought by SINR measurement and the effective elimination of interference through the conversion of this pilot structure.

A total of 2N pilot symbols are set in a frame. A signal is transmitted in an odd number of pilot symbols, and a signal is transmitted in an even number of pilot symbols. That is, the kth pilot symbol is:

among them:

P \ = cos (iyt + φ ₀ ) ~ Q _k sinOt + φ ₀ ) = Α _! _Ι cos («t + φ ₀ + φ _{Ι (} ) (^) p ₂ = I _k cosicot +.) ~ + Q _k sinict + φ ₀ ) = Α _Ιί cos (wt + φ ₀ - _k ) After fading the channel, the interference of fading factor and white noise is added. The form of the received signal is somewhat similar to the expression of formula (1). At this point:

·, 2Ν-1 ( _{Δ Λ} r _k 4 J

·, 2N The phase offset introduced for fading.

Because the interval between adjacent pilot symbols is short, Between (p _dk

2, NX Therefore, for 2k-1: 2k pilot symbols are:

r2k-

_{_{+ I 2k _, + n (}} 2k _ n (5) r2k = a 2k- \ A lk- \ C0S (+ ^ 0 + <P -l) - ί½- 1) + kl + n 2k (6) k = l, 2, ..., N

Referring to FIG. 4, at this time, the signal received by the receiving end is subjected to in-phase demodulation by the despreading and demodulation device 401, and output through the serial-to-parallel converter 403; quadrature demodulation is performed through the despreading and demodulation device 402, and serial and parallel The output of the converter 404 is obtained as follows:

^ (2k-\) s- ^a 2k-\-^ 2k- \ ^COS (^ 0 + ^ 24-1 + 9d (2k-l)) + (2Α-1) ^{+ H} s (2k ~ l) (7 ) ^ (2k-\) o ― ^a 2k-\-^ 2k- \ ^S i ⁿ (o ⁺ ^ (24-1)) ⁺ ^ o (2k- \) + ". (2A-1) (8) d _ks = a _2k A _2k cos (^ ₀ + (p _u -φ _άη ) + I _s2k + n _s2k (9) diko = a _lk A _2k sin (^ ₀ + φ _{2Ι [} _{-φ Λ2! ί} ) + I _olk + n _o2k (10) k = l, 2, ···, N

Arithmetic unit 405 is used to complete (7)-(9).

C _h = ~ 2 _k A _k sin ( ₀ + ^) sin (^) + n _k k = l, 3, 5 · · ·, 2N-1 (11) The arithmetic unit 406 is used to complete (8)-(10 ), Have:

C _h = 2a _k A _k cosO ₀ + ^) sin (¾) + n _k k = l, 3, 5 ·· ,, 2Ν-1 (12) where:

n sk ~ ^H sk ― ⁿ s (k + l) k = l, 3,5 ......, 2N-1 (13) ok ^{= n} ok ― ⁿ o (k) K = l, 3,5 ,, 2N-1 (14) n _k , n _k are all Gaussian white noise with zero mean.

It can be seen from the expressions of (11) and (12) that the noise has been basically eliminated. In order to accurately estimate the energy of the signal, the influence of white noise has to be removed. To do this, we need to average the formulas (11) and (12). The equalizers 407 and 408 average the expressions (11) and (12), respectively. Since there are 2N pilot symbols in total, through the above derivation process, after the subtraction operation between adjacent pilot symbols, only N terms are left in (11) and (12), so (11), ( 12) Take the average of N terms:

― \ N N J Ν

N 4 = i N _{k =]} N _{k = x}

After the average operation of (15) and (16), the influence of noise is largely eliminated, and because the reception interference of and the fading through the transmission channel have basically the same correlation, so

h = 2 _k A _k sin ( ₀ + φ _& ) sin (^) + n ' _s (17) c _ko = 2 _k A _k cos ( ₀ + φ _άίι ) sin () + n (18) at this time, It has become very small after averaging.

To get SINR measurements, you must get the total energy of the signal energy and interference and noise. Therefore, (17) * (17) + (18) * (18) is calculated by the operator 409, so that the energy of the estimated signal can be obtained.

E _sp = 4a _k ² A _k ² s ² ( _k ) + n- (19) Since the pilot symbol is a known signal, sin () is a known signal. From Equation (19) we can find 4 The precise signal energy, the calculator 412 is used to accomplish this function. The formula (19) is divided by the constant term 4 _S in ² (^), because the value of n "is very small and can be ignored here. The obtained signal energy is:

E _s = a _k ² A _k ² (20) The operator 410 is used to add the energy of each spreading chip within 2N symbols to obtain the total energy. Let the total energy be E, + „ ₊ , then calculate The total energy of the interference and noise can be obtained by the generator 411 as: E _{n + J} = E _{s + n} , ₁ -E _s (21) The divider 413 can find the final SINR as:

In the present invention, different pilot symbols with correlations between interference and fading are transmitted in the same subframe on the transmitting end, and the receiving end performs operations on the different pilot symbols to eliminate interference to obtain accurate SINR measurement . By using the SINR measurement technology provided by the present invention, accurate SINR measurement values can be given in the case of multi-cell multi-user interference, avoiding complicated multi-user detection, and is a communication system suitable for cellular mobile communication or interference. Effective SINR measurement method. The above is only described with a preferred embodiment of the present invention, and is not intended to limit the present invention. Any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention shall be included in the present invention. Within the scope of the claims.

Claims

Claim

1. A method for measuring a signal-to-interference and noise ratio (SINR) applied to a cellular mobile communication system, which is characterized in that the method includes:

Transmitting different pilot symbols in the same sub-frame at the transmitting end, interference between the different pilot symbols has correlation, and fading also has correlation;

The SINR measurement value is obtained at the receiving end by calculating the received different pilot symbols to eliminate interference.

2. The SINR measurement method according to claim 1, wherein: the different pilot symbols are composed of K different pilot symbols as a group, and transmitted.

2N pilot symbols in the 2N / K group, where K and NR are positive integers.

3. The SINR measurement method according to claim 2, wherein: K is 2, and two different pilot symbols of N groups are transmitted.

4. The SINR measurement method according to claim 2, wherein: K is 2N, and a group of 2N different pilot symbols is transmitted.

5. The SINR measurement method according to claim 1, wherein: the different pilot symbols are composed of K identical pilot symbols as a group, and a total of 2N of different 2N / K groups are transmitted. Pilot symbols, where K and N are positive integers.

6. The SINR measurement method according to claim 5, wherein: K is 2, and a total of 2N pilot symbols of different N groups are transmitted.

7. The SINR measurement method according to claim 5, wherein: K is N, and two different sets of 2N pilot symbols are transmitted.

8. The SINR measurement method according to any one of claims 1 to 7, characterized in that: the optimal setting of the different pilot symbols is such that the correlation characteristic value thereof is the smallest.

9. The SINR measurement method according to claim 1, wherein the The receiving end operates on the received different pilot symbols to eliminate interference, and obtaining the SINR measurement value includes the following steps:

(d) Calculate the total energy of the signal and subtract the signal energy of step c to obtain the total energy of interference and noise;

(e) Divide the signal energy by the total energy of interference and noise to get the SINR measurement.

10. The SINR measurement method according to claim 9, wherein: the different pilot symbols are composed of K different pilot symbols as a group, and transmitted.

2N pilot symbols in the 2N / K group, where K and NR are positive integers.

11. The SINR measurement method according to claim 10, wherein: K is 2, and transmitting N groups of 2N pilot symbols in total;

The subtraction operation of adjacent different pilot symbols after serial-parallel conversion refers to calculating a difference between pilot symbols of odd bits and pilot symbols of adjacent even bits.

12. The SINR measurement method according to claim 10, wherein: K is 2N, and a group of 2N different pilot symbols is transmitted;

The subtraction operation on serially-parallel converted adjacent different pilot symbols refers to calculating a difference between the M-th pilot symbol and the M-1-th pilot symbol, where M is less than or equal to 2N Positive even number.

13. The SINR measurement method according to claim 9, wherein: The different pilot symbols refer to a group consisting of K identical pilot symbols and transmitting a total of 2N pilot symbols of different 2N / K groups, where K and N are positive integers.

14. The SINR measurement method according to claim 13, wherein: K is 2, and a total of 2N pilot symbols are transmitted in different N groups;

The subtraction operation on serially-parallel converted adjacent different pilot symbols refers to calculating a difference between odd-numbered adjacent pilot symbols and an even-numbered adjacent pilot symbol.

15. The SINR measurement method according to claim 13, wherein: κ is N, and different 2 groups of 2N pilot symbols are transmitted;

The performing a subtraction operation on adjacent different pilot symbols after serial-parallel conversion refers to calculating a difference between a pilot symbol at the Mth bit and a pilot symbol at the (N + M) th position, where M is A positive integer less than or equal to N.

16. The SINR measurement method according to any one of claims 9 to 15, characterized in that: the optimal setting of the different pilot symbols is such that the correlation characteristic value thereof is the smallest.

17. A measuring device for signal-to-interference and noise ratio (SINR) applied to a cellular communication system, which is characterized by:

The device includes a despread in-phase demodulation device, a despread quadrature demodulation device, a serial-to-parallel converter, a subtracter, an equalizer, and an arithmetic unit;

The received signals are despread and demodulated by a despread in-phase demodulation device and a despread quadrature demodulation device; the despread and demodulated signals are each serial-parallel converted by a serial-parallel converter; Perform difference operation on adjacent different pilot symbols after serial-to-parallel conversion to eliminate interference; use the equalizer to accumulate and average the difference operation results to further eliminate interference; find the total energy by the operator, and divide the average. The operation results of the device are summed in a square to obtain the signal energy, and the total energy of interference and noise is further obtained. The SINR measurement value is obtained by dividing the signal energy by the total energy of interference and noise.