WO2011144073A2

WO2011144073A2 - Method and device for processing interference between base stations

Info

Publication number: WO2011144073A2
Application number: PCT/CN2011/074589
Authority: WO
Inventors: 张剑晖
Original assignee: 华为技术有限公司
Priority date: 2011-05-24
Filing date: 2011-05-24
Publication date: 2011-11-24
Also published as: WO2011144073A3; CN102204311A

Abstract

The invention relates to the field of communications, and discloses a method and a device for processing interference between base stations. The method includes that: a base station receives an improved type of uplink frame transmitted by a user terminal, and the head of the improved type of uplink frame is an idle subframe with predetermined time length; and the improved type of uplink frame is demodulated. The device includes a reception unit for the improved type of frame used to receive the improved type of uplink frame transmitted by the user terminal, the head of which is an idle subframe with predetermined time length, and an demodulation unit for the improved type of frame which is used to demodulate the improved type of uplink frame. The invention is mainly applied to a wireless communication system, and can reduce interference between base stations with the same frequency.

Description

Method and apparatus for handling inter-base station interference

The present invention relates to the field of communications, and in particular, to a method and apparatus for handling inter-base station interference. Background technique

In a wireless communication system, because the spectrum resources are limited, adjacent base stations with overlapping signal coverages use different frequency segments for signal transmission and reception, and non-adjacent base stations with no overlapping signal coverage use the same frequency segment.

In FIG. 1, base station A and base station B are non-adjacent base stations using the same frequency segment. In the downlink frame transmission period, base station A transmits downlink frame A, and base station B transmits downlink frame B. Under normal circumstances, the downlink frame A is attenuated, even if the signal coverage of the base station B does not cause interference to the base station B; however, when the location of the base station A is high, or there is a broad relationship between the base station A and the base station B. When the flat terrain is low, the downlink frame A may still have strong signal strength after entering the signal coverage of the base station B, so that after the uplink frame reception period comes, the downlink frame A is received by the base station B; in this case, The downlink frame A of the base station A causes the base station B to demodulate the uplink frame transmitted by the UE to the base station B. The downlink frame A and the downlink frame B in FIG. 1 reach the position shown in FIG. 2 at the beginning of the uplink frame reception period after the OT time elapses. In FIG. 2, the tail portion of the downlink frame A still does not pass through the base station B, so that the front end portion of the uplink frame C and the tail portion of the downlink frame A transmitted by the UE of the base station B simultaneously arrive at the base station B, and the downlink frame A and the uplink frame C simultaneously Received by the base station B, causing the demodulation of the uplink frame C to be interfered by the downlink frame A. Summary of the invention

Embodiments of the present invention provide a method and apparatus for handling inter-base station interference, which can reduce interference between intra-frequency base stations.

In order to achieve the above object, the embodiment of the present invention adopts the following technical solutions:

A method for handling inter-base station interference, comprising:

The base station receives the improved uplink frame transmitted by the UE, where the front end of the modified uplink frame is an idle subframe of a predetermined duration; Demodulating the improved upstream frame.

A device for processing inter-base station interference, comprising:

The improved frame receiving unit is configured to receive the improved uplink frame transmitted by the UE, where the front end of the improved uplink frame is an idle subframe of a predetermined duration;

An improved frame demodulation unit is configured to demodulate the improved uplink frame.

The method and device for processing inter-base station interference provided by the embodiment of the present invention, after receiving the improved uplink frame with the idle subframe, so that the downlink frame with the same frequency of the improved uplink frame transmitted by other base stations is delayed after transmission And being received by the base station at the same time as the idle subframe, so that when the base station demodulates the uplink frame, it is not affected by the downlink frame of the same frequency, and the downlink frame of the other base station is demodulated to the base station. The possibility of interference caused by the improved upstream frame.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a schematic diagram of a base station transmitting downlink frames using the same frequency segment;

2 is a schematic diagram of the uplink frame C and the downlink frame A transmitted by the UE being simultaneously received by the base station B after the t0 time elapses on the basis of FIG. 1;

3 is a schematic diagram of inter-base station interference in Embodiment 1 of the present invention;

4 is a flowchart of a method for processing inter-base station interference according to Embodiment 1 of the present invention; FIG. 5 is a block diagram of an apparatus for processing inter-base station interference according to Embodiment 1 of the present invention;

6 is a flowchart of a method for processing inter-base station interference according to Embodiment 2 of the present invention; FIG. 7 is a schematic diagram of a WIMAX frame structure;

8 is a schematic diagram of transmitting a downlink frame by a WIMAX base station using the same frequency in Embodiment 2 of the present invention;

9 is a schematic diagram of the interference caused by the downlink frame A not demodulating the uplink frame C by the base station B on the basis of FIG. 7;

FIG. 10 is a schematic diagram of the interference caused by the downlink frame A demodulating the uplink frame C by the base station B on the basis of FIG. 7;

FIG. 11 is a flowchart of a method for processing inter-base station interference in a WIMAX according to Embodiment 2 of the present invention; FIG. FIG. 1 is a schematic diagram of a modified uplink frame in a WIMAX system according to Embodiment 2 of the present invention; FIG. 13 is a schematic diagram of the second embodiment of the present invention, in the WIMAX system, by setting an idle subframe in the uplink frame C to avoid the downlink frame A. Schematic diagram of the interference of the base station B to demodulate the uplink frame C;

Figure 14 is a block diagram of an apparatus for handling inter-base station interference in Embodiment 3 of the present invention. detailed description

The technical solutions of the embodiments of the present invention are clearly and completely described in the following with reference to the accompanying drawings of the embodiments of the present invention. It is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments obtained by a person of ordinary skill in the art based on the embodiments of the present invention without creative work are within the scope of the present invention. Example 1

The process of the base station transmitting the downlink frame and receiving the uplink frame is time-division, as shown in FIG. In FIG. 3, the base station B sequentially performs downlink frame transmission and uplink frame reception. When the downlink frame of the base station A is transmitted to the base station B, if the base station B is receiving the uplink frame, the downlink frame of the base station A is demodulated for the base station B. The process of the upstream frame can cause interference. In this scenario, the embodiment of the present invention provides a method for processing inter-base station interference, as shown in FIG. 4, including the following steps:

1 01. The base station receives the improved uplink frame transmitted by the UE.

The front end of the improved uplink frame is an idle subframe of a predetermined duration. By setting an idle subframe of a predetermined length, the idle subframe is transmitted to the base station simultaneously with the downlink frame transmitted by the other base station and having the same frequency as the modified uplink frame.

1 02. Demodulate the improved uplink frame.

The front end portion of the modified uplink frame is set as an idle subframe, and when the base station performs demodulation on the modified uplink frame, the base station does not perform the demodulation action on the idle subframe, and arrives at the same time as the idle subframe. The downlink frame transmitted by other base stations of the base station and having the same frequency as the modified uplink frame does not interfere with the demodulation action of the base station. As a possible application scenario, the base station may perform a demodulation action on the idle subframe, because the idle subframe does not carry information that needs to be demodulated, and the idle subframe is Demodulation does not generate valuable data results, so downlink frames of the same frequency as the improved uplink frame transmitted by other base stations that arrive at the base station simultaneously with the idle subframe do not interfere with the demodulation action of the base station. . When the base station is to other parts of the improved upstream frame following the idle subframe The base station has passed through so as not to interfere with the demodulation action of the base station.

In the meantime, the embodiment of the present invention further provides a device for processing inter-base station interference, as shown in FIG. 5, including: an improved frame receiving unit 51 and an improved frame demodulating unit 52.

The improved frame receiving unit 51 is configured to receive the improved uplink frame transmitted by the UE, where the front end of the improved uplink frame is an idle subframe of a predetermined duration.

The improved frame demodulation unit 52 is configured to demodulate the improved upstream frame.

The method and device for processing inter-base station interference provided by the embodiment of the present invention, after receiving the improved uplink frame with the idle subframe, the downlink frame of the same frequency frame transmitted by the other base station is delayed after transmission. And being received by the base station at the same time as the idle subframe, so that the base station performs demodulation is not affected by the downlink frame of the same frequency, and the downlink frame of the other base station is reduced to demodulate the improved uplink to the base station. The possibility of frames causing interference.

Example 2:

The embodiment of the invention provides a method for processing inter-base station interference, as shown in FIG. 6, which includes the following steps:

201. The base station receives the improved uplink frame transmitted by the UE.

The front end of the improved uplink frame is an idle subframe of a predetermined duration. By setting an idle subframe of a predetermined length, the idle subframe is transmitted to the base station simultaneously with the downlink frame transmitted by the other base station and having the same frequency as the modified uplink frame. The other part of the modified uplink frame except the idle subframe is a non-idle subframe.

The predetermined duration of the idle subframe may be set according to a distance between the base station and other base stations, and a difference between predetermined base station distances in which transmission of the downlink frame does not cause interference to the reception of the uplink frame. set. Regarding the related description of the time value setting of the predetermined duration, reference may be made to the description of setting the idle subframe in the WINMAX system below in the embodiment of the present invention.

202. Determine whether the currently received uplink subframe is a non-idle subframe.

The base station detects an uplink subframe of the received improved uplink frame, and if the uplink subframe is the idle subframe, the base station does not perform demodulation on the idle subframe; if the uplink subframe For the non-idle subframe, go to step 203.

203. When the received uplink subframe is the non-idle subframe, the base station is configured to The non-idle subframe is demodulated.

The front end portion of the modified uplink frame is set to the idle subframe. When the idle subframe arrives at the base station, the base station does not perform a demodulation action on the idle subframe, and the idle child A downlink frame transmitted by another base station that arrives at the base station at the same frequency as the modified uplink frame does not interfere with the demodulation action of the base station. The idle subframe that is not behind the same uplink frame of the non-idle subframe arrives at the base station. When the non-idle subframe arrives at the base station, the downlink frame transmitted by the other base station and the same frequency as the modified uplink frame has completely passed the base station, and does not interfere with the base station to the non-free child. Demodulation of the frame. Certainly, as a feasible application scenario, the base station may perform a demodulation action on the idle subframe, but the idle subframe does not have information to be demodulated, and thus the entire improved uplink The demodulation result of the frame has no effect.

As an optional practical application scenario, the method provided by the embodiment of the present invention is in use.

The OFDMA (Orthogonal Frequency Division Multiple Access) technology has a wide range of applications in TDD (Time Division Duplex) wireless communication systems.

WIMAX (Wor ldwide Interoperability for Microwave Access) is a wireless metropolitan area network broadband access technology based on IEEE802.16. The WIMAX system using OFDMA and TDD technology, the structure of the uplink frame transmitted by the UE to the base station is shown in Figure 7. The first three symbols Symbol ( symbolO, symbol symbol2 ) in the time domain are defined by the protocol as a common area. In addition, in the WIMAX system, there is a fixed transmission and reception gap between the downlink frame transmission period and the uplink frame reception period. Taking a 10 M bandwidth W I MAX system as an example, the transmission and reception gap is 105.71 us (microseconds). It is possible to take the electromagnetic wave transmission speed to 300000km/s, and you can get:

300000*105.7/1000000 = 31.7km

For the base station A and the base station B in the WIMAX system, the distance between the two base stations is S (S 31.7 km). During the downlink frame transmission period, the base station Α and the base station 发射 respectively transmit the downlink frame A and the downlink frame B, if the two frames are at If the transmission is in the same direction, the spacing between the frame headers of the two frames is S. It is assumed that at the end of the downlink frame transmission period, the downlink frame A and the downlink frame B are completely transmitted from the base station, as shown in FIG. On the basis of FIG. 8, the downlink frame A and the downlink frame B are transmitted again after 105.71 us, and the base station enters the uplink frame reception period, and starts to receive the uplink frame C uploaded by the user terminal, as shown in FIG. In FIG. 9, the downlink frame A has passed through the base station B. At this time, even if the downlink frame A still has strong signal strength after receiving the signal coverage range of the base station B, and is received by the base station B, it does not cause interference to the base station B to demodulate the uplink frame C. However, in the case shown in FIG. 10, the distance S1 between the base station A and the base station B is greater than 31.7 km, and then, when the uplink frame reception period comes, the tail of the downlink frame A still does not reach the base station B, and the base station B simultaneously receives. The downlink frame A and the uplink frame C of the UE, the downlink frame A will interfere with the demodulation of the front end portion of the uplink frame C, and is defined as HARQ (Hybrid Automatic Repeat Reques t) in the first three symbols of the common area. The ACK information, the CQICH (Channel Quality Information Channel) information, and the like of the retransmission request, and the interference caused by the demodulation of the first three symbols will greatly deteriorate the uplink service of the base station B.

The WIMAX system in the TDD wireless communication system using the 0FDMA technology is taken as an example to describe a method for handling inter-base station interference according to an embodiment of the present invention. As shown in Figure 11, the method includes the following steps.

301. The WIMAX base station receives the improved uplink frame transmitted by the UE.

In the WIMAX system, in order to reduce the interference of the downlink frame to the uplink frame, the structure of the uplink frame may be adjusted in advance, and three consecutive symbols of the frame header of the uplink frame are vacated. Taking the frame structure in FIG. 7 as an example, the symbolO is vacated. The information of the common area to symbol2, symbol 0 to symbol 2 is moved back to symbol3 to symbol5, and the structure of the improved upstream frame is shown in FIG.

The three symbols vacated at the front end of the modified uplink frame are defined as idle subframes, and the predetermined duration of the idle subframes is the duration of three symbols vacated by the front end. For example, the idle subframe can be set to a safety zone according to the WIMAX protocol, and the base station does not perform a demodulation action on the safety zone. After the downlink frame of the same frequency of the modified uplink frame transmitted by the other WIMAX base station is subjected to the transmission delay, the uplink frame reception period and the first three symbols of the improved uplink frame arrive at the WIMAX base station simultaneously, and are Said WIMAX base station reception.

The front end of the modified uplink frame is set as an idle subframe with a duration of 3 symbols, and the original information content (ACK information, CQICH information, etc.) in the front 3 symbols is correspondingly moved into the following symbol, when the WIMAX When the base station demodulates the information content of the symbol that is moved into the following, it is not interfered by the downlink frame transmitted by the other WIMAX base station and the same uplink frequency of the modified uplink frame. The other part of the improved uplink frame except the idle subframe is a non-idle subframe.

302. Determine whether an uplink subframe of the currently received improved uplink frame is a non-idle subframe.

The WIMAX base station detects an uplink subframe of the received improved uplink frame, and if the uplink subframe is the idle subframe, the WIMAX base station does not perform demodulation on the idle subframe; The subframe is the non-idle subframe, and the process proceeds to step 303.

303. When the received uplink subframe is the non-idle subframe, the WIMAX base station demodulates the non-idle subframe.

In the case where the first three symbo l (symbo l O , symbo l symbo l 2 ) of the improved uplink frame in the WIMAX system are set to the idle subframe, when the idle subframe arrives at the base station The WIMAX base station does not perform a demodulation action on the idle subframe. In this case, the demodulation actions of other WIMAX base stations that arrive at the WIMAX base station simultaneously with the idle subframe cause interference.

The non-idle subframe lags behind the idle subframe in the same uplink frame to reach the WIMAX base station. When the non-idle subframe arrives at the WIMAX base station, the downlink frame of the same frequency as the modified uplink frame transmitted by the other WIMAX base station has completely passed the WIMAX base station, and does not interfere with the base station Demodulation of non-idle subframes. The WIMAX base station performs demodulation of the improved upstream frame from symbo.

Still taking the case of FIG. 10 as an example, when the uplink frame C arrives at the base station B, the tail portion of the downlink frame A still does not pass through the base station B. If the uplink frame C is the modified uplink frame, the first three symbos of the uplink frame C For the idle subframe, according to the WIMAX protocol, a symbo l duration of the WIMAX system with a bandwidth of 10 0 is 102.86 us, and the duration of the first three symbos is 308.58 us. That is, the idle subframe consisting of symbo l O to symbo l 2 needs 308. 58us through the base station B. In 308.58us, the downlink frame A of the base station A has already passed the base station B, and does not belong to the base station B. Demodulation of the upstream frame C causes interference, as shown in Figure 13.

Of course, as a feasible application scenario, the WIMAX base station may perform a demodulation action on the idle subframe, but the idle subframe does not have information to be demodulated, and thus the entire improved type The demodulation result of the upstream frame has no effect.

In the case where the distance S 1 between the base station A and the base station B is greater than 31. 7 km, when When the predetermined duration of the idle subframe is not less than (S 1- 31. 7 ) / 300000, the downlink frame of the same frequency as the modified uplink frame transmitted by the other WIMAX base station arrives at the WIMAX base station, and the WIMAX is not The base station demodulates the downlink frame to cause interference. The WIMAX protocol specifies that the WIMAX base station processes the uplink frame in units of three symbos. Therefore, the duration of the idle subframe is at least three symbos. Further, the duration of the idle subframe may also be set to 6 symbo l (symbo l 0 to symbo l 5 ) or 9 symbo l (symbo l 0 to symbo l 8 ), etc., the original information content in the idle subframe is correspondingly moved into the following symbo l. When the base station B demodulates the information content of the symbo l that is moved into the following, the method in the embodiment of the present invention may also be used in other wireless communication systems that use OFDM, for example, an LTE network that communicates in a TDD manner. .

The method for processing inter-base station interference provided by the embodiment of the present invention reduces the possibility that the downlink frame of another base station interferes with the base station demodulating the improved uplink frame by receiving the improved uplink frame with the idle subframe. . In particular, in a WIMAX system using the OFDM technology and the TDD technology, the WIMAX base station receives the idle subframe of the improved uplink frame and also receives the downlink frame transmitted by the other WIMAX base station and the same frequency as the modified uplink frame. The idle subframe does not have content to be demodulated, thereby avoiding interference of downlink frames of other WIMAX base stations to demodulation.

Example 3:

An embodiment of the present invention provides an apparatus for processing inter-base station interference. As shown in FIG. 14, the method includes: an improved frame receiving unit 141, an improved frame demodulating unit 142, and the improved frame demodulating unit 142 further includes an improvement. Type frame demodulation subunit 1421.

The modified frame receiving unit 141 is configured to receive the improved uplink frame transmitted by the UE, where the front end of the improved uplink frame is an idle subframe of a predetermined duration.

The improved frame demodulation unit 142 is configured to demodulate the improved upstream frame.

The improved frame demodulation sub-unit 1421 is configured to demodulate the non-free subframe when the uplink subframe in the modified uplink frame is a non-idle subframe.

The front end portion of the modified uplink frame is set as an idle subframe, and when the base station performs demodulation on the modified uplink frame, the base station does not perform the demodulation action on the idle subframe, and arrives at the same time as the idle subframe. The downlink frame transmitted by other base stations of the base station and having the same frequency as the modified uplink frame does not interfere with the demodulation action of the base station. Of course, as a feasible The application scenario, the base station may perform a demodulation action on the idle subframe. Since the idle subframe does not carry information that needs to be demodulated, demodulation of the idle subframe does not occur. As a result of the data of the value, the downlink frame transmitted by the other base stations simultaneously reaching the base station and having the same frequency as the modified uplink frame does not interfere with the demodulation action of the base station.

As an optional practical application scenario, the device provided by the embodiment of the present invention is in use.

0FDMA technology has a wide range of uses in TDD wireless communication systems such as WIMAX systems. For a description of the inter-base station interference in the WIMAX system, refer to the description in Embodiment 2 of the present invention, and details are not described herein again.

The apparatus for processing inter-base station interference provided by the embodiment of the present invention, after receiving the improved uplink frame with the idle subframe, causes the downlink frame of the same frequency frame transmitted by the other base station to pass the transmission delay delay The idle subframes overlap in the time domain, so that the base station performs demodulation without being affected by the downlink frames of the same frequency, and the downlink frames of the other base stations are reduced to demodulate the improved uplink frame by the base station. The possibility of interference.

Through the description of the above embodiments, those skilled in the art can clearly understand that the present invention can be implemented by means of software plus necessary general hardware, and of course, by hardware, but in many cases, the former is a better implementation. . Based on such understanding, the technical solution of the present invention, which is essential or contributes to the prior art, may be embodied in the form of a software product stored in a readable storage medium, such as a floppy disk of a computer. A hard disk or optical disk, etc., includes instructions for causing a computer device (which may be a personal computer, server, or network device, etc.) to perform the methods described in various embodiments of the present invention.

The above is only the specific embodiment of the present invention, but the scope of the present invention is not limited thereto, and any person skilled in the art can easily think of changes or substitutions within the technical scope of the present invention. It should be covered by the scope of the present invention. Therefore, the scope of the invention should be determined by the scope of the claims.

Claims

Claim

A method for processing inter-base station interference, comprising:

The base station receives the improved uplink frame transmitted by the UE, where the front end of the modified uplink frame is an idle subframe of a predetermined duration;

Demodulating the improved upstream frame.

2. The method according to claim 1, wherein the demodulating the improved uplink frame further comprises:

When the uplink subframe in the improved uplink frame is a non-idle subframe, the base station demodulates the non-free subframe.

The method according to claim 1 or 2, characterized in that: according to the distance between the base station and other base stations, and between the predetermined inter-base station distances in which the transmission of the downlink frame does not cause interference to the reception of the uplink frame And determining, by the difference, the predetermined duration; wherein, the base station and the frequency frame.

The method according to claim 1 or 2, wherein in the TDD time division duplex WIMAX wireless network system, the predetermined duration is three adjacent SYMBOL symbols in the WIMAX frame, or six SYMBOL symbols. .

5. A device for processing inter-base station interference, comprising:

The apparatus according to claim 5, wherein the improved frame demodulation unit comprises: demodulating the non-idle subframe when an idle subframe is used.

7. The apparatus according to claim 5 or 6, wherein the distance between the base station and other base stations, and the distance between the predetermined base stations in which the transmission of the downlink frame does not cause interference to the reception of the uplink frame And determining, by the difference, the predetermined duration; wherein, the base station and the frequency frame.

8. Apparatus according to claim 5 or claim 6 wherein duplexing is performed in TDD In a WIMAX wireless network system, the predetermined duration is three adjacent SYMBOL symbols in a WIMAX frame, or six SYMBOL symbols.