CN100393161C - A method of improving frequency band utilization by utilizing the space division characteristic of the array - Google Patents

Abstract

The invention discloses a method for improving frequency band utilization by utilizing the space division characteristics of an array, which includes the following steps: according to the array capability of a base station, a 360° omnidirectional cell covered by a circular array is split into a plurality of corresponding sub-cells, so that The user arrival direction corresponding to each sub-cell is set to 0-α ₁ °, α ₁ °α ₂ °, ..., α _n-1 °-α _n °, where α ₁ °+α ₂ °... ...+α _n-1 °+α _n °=360°, n is an integer greater than 2, and assigning 1 scrambling code and 1 basic training sequence code to each of the sub-cells; for each of the sub-cells All users in each time slot generate physical channel resources; demodulate sub-cells for the received signals of the elements. The method can greatly increase the user capacity of the wireless communication network system and improve the utilization rate of the frequency band.

Description

A method of improving frequency band utilization by utilizing the space division characteristic of the array

technical field

The present invention relates to a kind of method that utilizes the space division characteristic of array to improve the frequency band utilization rate of system in various communication systems in FDMA/TDMA/CDMA, especially relates to the space division characteristic of utilizing array in WCDMA TDD and TD-SCDMA mobile communication system A method to improve the frequency band utilization of the system.

Background technique

In all existing mobile communication systems, one or more combinations of frequency division (FDMA), time division (TDMA) or code division (CDMA) characteristics of wireless resources are usually used to form a multiple access system, providing a large number of mobile users Provide services such as TACS (FDMA), GSM (FDMA/TDMA), IS-95 (FDMA/CDMA), WCDMA (FDMA/CDMA), TD-SCDMA (FDMA/TDMA/CDMA). In a cell, the wireless resources occupied by different users must not be all the same, which greatly limits the system frequency band utilization and limits the user capacity within a unit frequency band. But at the same time, it can also be seen that any method that can introduce the independent characteristics of wireless resources will bring about a significant increase in frequency band utilization. For example, because TD-SCDMA uses FDMA/TDMA/CDMA to allocate resources, its frequency band utilization rate is far higher than other systems.

With the continuous maturity of smart antenna technology, beamforming technology with space division characteristics can dynamically (or fixedly) divide cells to form several sub-cells. In these sub-cells, the three characteristics of existing wireless resources can be repeated. use. In particular, the beam coverage (sub-cell) formed based on smart antenna technology can be dynamically adjusted according to specific requirements (such as traffic volume), which has great flexibility; at the same time, it can make up for the pilot pollution caused by the existing sector splitting technology and other issues; it greatly reduces system cost, increases system capacity, reduces system interference, and increases cell coverage.

WCDMA TDD and TD-SCDMA mobile communication systems have built a good physical foundation for the successful realization of smart antenna technology by designing a unique frame structure and adopting TDD duplex mode. In fact, the mobile communication system must select the key technology, but this does not affect the improvement of the present invention to other mobile communication systems.

Literature [1] defines the physical layer frame structure of the existing TD-SCDMA system, the corresponding time slot results and the data structure of each burst. According to the definition, on an existing carrier frequency point, the same scrambling code and a basic training sequence (Midamble code for short) are configured in the same cell, and only 16 code channels can be configured in the same time slot (currently, a time slot can be configured with a maximum of 16 code channels). It can only support 8 12.2k voice users, and the same carrier can support up to 24 12.2k voice users). The Midamble codes used by different users on the same time slot are all generated by the basic Midamble codes after cyclic shifting, and the corresponding channel estimation methods generally use the Steinet estimation method [2], which is a low-cost channel Estimation method. In order to improve the performance, in the literature [3], a noise reduction post-processing method for threshold detection is proposed. The basic idea is to use the Steiner estimation method to estimate the original channel impulse response first, and then use a threshold to remove most of the noise. tap. Literature [4] explained in detail the joint detection and demodulation technology adopted in the TD-SCDMA system.

Among them, literature ^[1] : 3GPP TS 25.221: "Physical channels and mapping of transport channels onto physical channels (TDD)".

Literature ^[2] : STEINER B, BAIER P. Low cost channel estimation in the uplink receiver of CDMA mobile radio systems, Frequenz, 1993, 47(12): 292-298.

Literature ^[3] : Kang Shaoli, Qiu Zhengding, etc. Improvement of low-cost channel estimation method in TD-SCDMA system. Journal of Communications, 2002, 23(10): 125-130.

Literature ^[4] : A.Clein "Zero Forcing and Minimum Mean-Square-ErrorEqualization for Multiuser Detection in Code-DivisionMultiple-Access Channels"

Contents of the invention

The technical problem to be solved by the present invention is to provide a specific wireless resource configuration method and corresponding demodulation technology, which greatly improves the user capacity of the wireless communication network system and improves the frequency band utilization.

In order to achieve the above object, the present invention provides a method for improving frequency band utilization by using the space division characteristics of the array, which is characterized in that it includes:

Step 1, according to the array capability of the base station, a 360 ° omnidirectional cell covered by the circular array is split into a plurality of corresponding sub-cells, so that the user incoming wave direction corresponding to each of the sub-cells is set to 0-α ₁ °, α ₁ °-α ₂ °, ..., α _n-1 °-α _n °, wherein, α ₁ °+α ₂ °......+α _n-1 °+α _n °=360°, n=greater than 2 An integer of , and assigning 1 scrambling code and 1 basic training sequence code to each of the sub-cells;

Step 2, generating physical channel resources for all users in each time slot in each sub-cell;

Step 3, performing sub-cell demodulation on the received signal of the cell.

In the above-mentioned method for improving frequency band utilization, the second step further includes: judging the sub-cell to which the user belongs according to the direction of arrival of the main wave of the user during the initial access process; generating a training sequence, according to each of the The basic training sequence code allocated by the sub-cell and the maximum number of users that need to be admitted are used to generate the training sequence of each user in the sub-cell; the physical code channel resources are allocated, and the user is assigned a unique A certain number of physical code channels;

The data part of all sub-cell users is scrambled with the scrambling code allocated by the sub-cell.

计算出用户分配的传输信道窗长W，然后利用Steriner技术为每个用户产生训练序列。The above method for improving frequency band utilization, wherein, in the step of generating the training sequence, the formula

Calculate the transmission channel window length W allocated by users, and then use Steriner technology to generate training sequences for each user.

The above method for improving frequency band utilization, wherein, in the step of allocating physical code channel resources, the physical code channel is performed according to the physical layer frame structure of the TD-SCDMASA system, the corresponding time slot results and the data structure of each burst. Allocation of resources.

The above-mentioned method for improving frequency band utilization, wherein, said step three further includes:

Step a, weighting the array element data into beam domain data;

Step b, for each beam domain data, separate the training sequence received signal from it, and perform channel estimation and channel post-processing on the sub-cell users;

Step c, for each beam domain data, separate the user data received signal from it, and then estimate the channel impulse response of each user in the sub-cell according to step b, and then demodulate the user data in the sub-cell;

In step d, the operations of step a to step c are performed on all sub-cells.

In the above-mentioned method for improving frequency band utilization, the step a is to perform weighting processing on array received signals according to the beam weights designed for each sub-cell.

In the above method for improving frequency band utilization, the step b is to use the Steriner channel estimation method and set the noise threshold to perform post-noise reduction processing.

In the above-mentioned method for improving frequency band utilization, wherein, in step c described in d, joint detection and demodulation technology or RAKE technology is used to demodulate user data in the cell.

In the above method for improving frequency band utilization, in step 1, the scrambling code and the basic training sequence code assigned to each sub-cell are the same or different.

In the above method for improving frequency band utilization, in step 1, n=3 or 6.

By adopting the cell code allocation method proposed based on the array space division characteristics of the present invention and the corresponding demodulation method based on this allocation method, the system capacity and the flexibility of the sub-cell space are greatly improved.

Description of drawings

Fig. 1 is the schematic diagram that an omnidirectional sub-district covered by a circular array is split into 3 sub-districts (taking the average split as an example, it can also be split unevenly);

Fig. 2 is a schematic diagram of training sequence generation of all users in each time slot in each sub-cell;

Figure 3 is a flowchart of the demodulation of the received signal of the array element.

Specific implementation steps

According to literature ^[1] , for any communication frequency point, one downlink synchronization pilot code DwPTS, eight uplink random access codes UpPTS, one scrambling code and one basic Midamble code are configured in the cell parameters; in fact, there are three more The scrambling code and the corresponding three basic Midamble codes are not allocated.

The present invention utilizes the space division feature (or interference suppression feature) of the array to split a cell into several sub-cells in space, and the code resources of each sub-cell can be completely reconfigured, or one scrambling code and one scrambling code can be configured for each sub-cell. 1 base Midamble code. In each sub-cell, there is only one scrambling code and basic Midamble code, and correspondingly, the number of code channels in each sub-cell can be configured up to 16.

In the corresponding demodulation method, firstly, the array signal is weighted by using the designed array weights, that is, the array element domain signal is transformed into a sub-small area (i.e. beam domain) signal; and then the sub-small area (i.e. beam domain) ) signal is demodulated according to the method introduced in literature ^[2] - literature ^[4] .

The present invention discloses a cell code assignment method based on array space division characteristics, and a corresponding demodulation method based on this assignment method, which includes the following steps (taking the circular array as an example, referring to Fig. 1):

Step 1: According to the array capability of the base station, it can be planned to split an omnidirectional (360-degree) cell into 3 (or 6 or other, take 3 as an example) corresponding sub-cells, and the users corresponding to each sub-cell come The wave direction is 0-120 degrees, 120-240 degrees, 240-360 degrees (for the sake of illustration, these sub-cells are numbered in order of sub-cell 1, sub-cell 2, and sub-cell 3), and each sub-cell is assigned a scrambling code and one basic Midamble code (the scrambling codes and basic Midamble codes of different sub-cells can be the same or different, but in order to reduce the control complexity, the general configurations are different).

The second step: generate physical channel resources for all users in each time slot in each sub-cell, which can be divided into the following steps:

(1) First, according to the direction of arrival of the main wave of the user in the initial access process, determine the sub-cell to which the user belongs;

(2) Generate a training sequence: generate a training sequence for each user in the sub-cell according to the basic Midamble code assigned to each sub-cell and the maximum number of users K to be admitted. ready-to-use Calculate the transmission channel window length W allocated by the user, and then generate a training sequence for each user according to the literature ^[2] .

(3) Allocate physical code channel resources: according to the scrambling code allocated by each sub-cell, the user can be allocated a unique and a certain number of physical code channels according to the method of literature [1]; finally, the data part of all sub-cell users The scrambling code assigned to this sub-cell needs to be used for scrambling.

The third step: Demodulate the received signal of the array element, which can be divided into the following steps:

(1) Weight the array element data into sub-cell data, that is, beam domain data: firstly, according to the beam weights that have been designed for each sub-cell, the array received signal is weighted, that is, the array element data is weighted into sub-cell data (that is, beam domain data domain data).

(2) For each sub-cell data (that is, beam domain data), separate the training sequence reception signal from it, and then perform channel estimation and channel post-processing on the users in this sub-cell according to the methods introduced in literature ^[2] and literature ^[3] .

(3) For each sub-cell data (i.e., beam domain data), separate the user data reception signal from it, and then estimate the channel impulse response of each user in this sub-cell according to (2), and then follow the method introduced in [4] or Other methods (such as RAKE technology) demodulate the user data of the sub-cell.

(4) Perform operations (1)-(3) for all sub-cells.

Above-mentioned method is mainly for WCDMA TDD and TD-SCDMA mobile communication system by design, certainly, also can all carry out with reference to main thought of the present invention to the improvement of other systems.

In order to better understand the present invention, the specific embodiments of the technical solution will be further described in detail below in conjunction with the accompanying drawings.

Referring to Figure 1, each sub-cell is assigned one scrambling code and one basic Midamble code (the scrambling codes and basic Midamble codes of different sub-cells can be the same or different, but in order to reduce the control complexity, the general configurations are different).

计算出用户分配的传输信道窗长W，如图2所示，为每个用户产生训练序列。According to the incoming direction of the main wave of the user during the initial access process, the sub-cell to which the user belongs is judged. The training sequence of each user in the sub-cell is generated according to the basic Midamble code allocated by each sub-cell and the maximum number K of users to be admitted. ready-to-use

Calculate the transmission channel window length W allocated by the user, as shown in Figure 2, and generate a training sequence for each user.

In Figure 3, sub-cell demodulation is performed on the received signal e of the element:

The user data reaches the receiver through spread spectrum scrambling and air channel, and receives the superimposed signals of the three sub-cells. Considering the received noise and interference, the received signal is written in matrix form:

e _ka =A _{1, ka} d ₁ +A _{2, ka} d ₂ +A _{3, ka} d ₃ +n _ka

A _{i, ka} , i=1, 2, 3; k _a =1, 2,..., the K _a matrix includes information on the spread spectrum scrambling codes and channel impulse responses of the three sub-cells respectively; K _a indicates that there are K _a antennas; d _i , i=1, 2, 3 represent their transmitted data, n represents the noise received by the receiver.

Firstly, according to the beam weight w _{i, ka} designed for each sub-cell, i=1, 2, 3, the received signal of the array is weighted, that is, the array element data is weighted into the sub-cell data e _i (that is, the beam domain data ),

$e_i=\underset{k_a=1}{\overset{K_a}{\mathrm{\Σ}}}{w}_{i,k_a}^h{e}_{k_a},$ i=1,2,3

Since the beam weight of each sub-cell includes the directional characteristics of the sub-cell, the data of the sub-cell can be separated, while signals of other sub-cells are suppressed.

Then, for each sub-cell data (ie, beam domain data), separate the training sequence received signal from it, and complete channel estimation and channel post-processing for users in this sub-cell,

${\hat{h}}_i=G_i^{-1}\·e_i,$ i=1,2,3

G _i , i=1, 2, 3 matrices are cyclic right-shift matrices composed of 3 basic training sequence codes (Midamble codes, allocated when generating physical channel resources for all users in each time slot in each sub-cell) .

进行信道后处理，小于判决门限的置为零。用经过信道后处理的

对本子小区用户数据解调。用3个子小区各自的扩频扰码和后处理的信道冲激响应

生成矩阵A_i，对数据域用下式进行估计：Set a noise threshold T _i , the estimated

Perform channel post-processing, and set the value smaller than the decision threshold to zero. post-channel processing

Demodulate the user data of the sub-cell. Channel impulse response using the respective spreading scrambling codes and post-processing of the 3 sub-cells

Generate the matrix A _i , and use the following formula to estimate the data domain:

${\hat{d}}_i={(A_i^h\·A_i)}^{-1}{A}_i^h{e}_i,$ i=1,2,3

Thus, the demodulation data of each user is obtained.

Compared with the prior art, the present invention discloses a cell code sub-allocation method based on the space division characteristics of the array, and a demodulation method corresponding to this allocation method, which generates 6 fixed beams (6 sub-cells) according to an 8-antenna circular array ), each sub-cell can accommodate 4 12.2k voice users (up to 8 12.2k voice users) per time slot, and can accommodate 24 12.2k voice users (theoretically speaking, it can accommodate 48), and its system capacity is far It is much higher than the existing level of 8 12.2k voice users per time slot, which greatly improves the frequency band utilization of the system.

The invention is applicable to all FDMA/TDMA/CDMA systems, especially to WCDMA TDD and TD-SCDMA systems in the current third generation mobile communication system. However, it should be understood that although the technical solution of the present invention is mainly aimed at wireless communication systems with code division multiple access, it is also applicable to frequency division multiple access and time division multiple access systems using similar transmission structures, any system with signal processing, communication, etc. Engineers with knowledge background can design corresponding channel estimation devices according to the present invention, which should be included in the idea and scope of the present invention.

Claims (10)

1. a method of utilizing the sky branch characteristic raising band efficiency of array is characterized in that, comprising:

Step 1 according to the array capability of base station, with justifying the sub cell that gust 360 ° of omni cell that cover split into a plurality of correspondences, makes arrival bearing user of each described sub cell correspondence be set to 0-α ₁°, α ₁°-α ₂° ..., α _N-1°-α _n°, wherein, α ₁°+α ₂° ...+α _N-1°+α _n°=360 °, n is the integer greater than 2, and is that each described sub cell distributes 1 scrambler and 1 basic training sequences sign indicating number;

Step 2 is for all users of each time slot in each described sub cell produce physical channel resources;

Step 3 is carried out the sub cell demodulation to the array element received signal.

2. the method for raising band efficiency according to claim 1 is characterized in that, described step 2 comprises again:

Main ripple arrival bearing according to user in the initial access process judges the sub cell that this user belongs to;

Produce training sequence, maximum user's number that basic training sequences sign indicating number that distributes according to each described sub cell and needs are admitted produces the training sequence of each user in the described sub cell;

Distribute the physics code channel resource, according to the scrambler of each sub cell distribution, for this user distributes physical code channel unique, some;

To all sub cell user's data partly with the book cell allocation to scrambler carry out scrambling.

3. the method for raising band efficiency according to claim 2 is characterized in that, in the step that produces training sequence, adopts formula , calculate the long W of transmission channel window that the user distributes, utilize the Steriner technology to produce training sequence then for each user; Wherein, P represents the basic training sequences sign indicating number that each described sub cell distributes, and K represents maximum user's number that needs are admitted.

4. the method for raising band efficiency according to claim 2, it is characterized in that, in the step of distributing the physics code channel resource, be the data structure of the physical layer frame structure according to the TD-SCDMASA system, corresponding time slot result and each burst, carry out the distribution of physical code channel resource.

5. the method for raising band efficiency according to claim 1 is characterized in that, described step 3 comprises again:

Step a is weighted to the wave beam numeric field data to the array element data;

Step b to each wave beam numeric field data, therefrom isolates the training sequence received signal, and this described sub cell user is carried out channel estimating and channel post-processing;

Step c to each wave beam numeric field data, therefrom isolates the user data received signal, estimates the channel impulse response of book users of all cells then according to step b, then to book community user data demodulates;

Steps d is carried out the operation of step a-step c to all sub cells.

6. the method for raising band efficiency according to claim 5 is characterized in that, described step a is the wave beam weight that has designed according to each sub cell, and the array received signal is weighted processing.

7. the method for raising band efficiency according to claim 5 is characterized in that, described step b adopts Steriner channel estimating method and utilizes the setting noise gate to carry out the noise reduction reprocessing.

8. the method for raising band efficiency according to claim 5 is characterized in that, among the described step c, is to adopt joint-detection demodulation techniques or RAKE technology to this community user data demodulates.

9. the method for raising band efficiency according to claim 1 is characterized in that, in step 1, the scrambler that distributes for each sub cell is identical with the basic training sequences sign indicating number, or inequality.

10. the method for raising band efficiency according to claim 1 is characterized in that, in step 1, and n=3 or 6.

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