WO2012151984A1

WO2012151984A1 - Method and system for eliminating adjacent channel interference

Info

Publication number: WO2012151984A1
Application number: PCT/CN2011/083815
Authority: WO
Inventors: 黄旭; 胡云玩
Original assignee: 中兴通讯股份有限公司
Priority date: 2011-08-12
Filing date: 2011-12-12
Publication date: 2012-11-15
Also published as: CN102932798A

Abstract

Disclosed is a method for eliminating adjacent channel interference. The method comprises: acquiring related information of an adjacent channel downlink signal, and obtaining an interference signal; eliminating the interference signal from a received uplink signal. Also disclosed is a system for eliminating adjacent channel interference. Adjacent channel interference can be eliminated without setting any guard band between adjacent channels, thereby saving spectrum resources, fully taking advantage of the spectrum resources, and improving the spectrum utilization.

Description

Method and system for eliminating adjacent frequency interference

The present invention relates to signal processing techniques in the field of wireless communications, and more particularly to a method and system for eliminating adjacent frequency interference. Background technique

Wireless communication systems are rapidly evolving around the world, accompanied by increasing frequency of wireless spectrum resources. In order to ensure the normal development of various applications, each country and region performs spectrum division under the unified coordination of ITU, and in order to prevent interference between adjacent frequencies, a protection isolation band is defined between the frequency bands occupied by each application. The protective isolation barrier cannot carry any useful information. The protection of the isolation strap is not only dependent on the application characteristics of the occupied frequency band, but also the performance level of the current RF filter. In the Long-Term Evolution (LTE) communication system, 4, such as the frequency division duplex (FDD), the lOMhz band is adjacent to the lOMhz band of Time Division Duplexing (TDD). Under the requirements of the co-location station, it is necessary to set up a protection isolation band around lOMhz. The protection isolation band of lOMhz cannot carry any useful information, and the band resource of lOMhz will be enough to run a TDD network. Therefore, the elimination of interference between adjacent frequencies by setting up a protective isolation band will result in a huge waste of resources.

For a communication system in which two adjacent frequencies coexist, for example, a TDD system C1 and an FDD system C2, wherein the TDD system C1 includes a system transceiver S1 and a terminal transceiver UE-1, and the FDD system C2 includes a system transceiver S2 and a terminal transceiver. UE 2, when the adjacent frequency coexists between the TDD system C1 and the FDD system C2, the interference that occurs is divided into four scenarios:

First, the system transceiver S1 transmits a signal to the UE-1, and the system transceiver S2 receives the signal sent by the UE-2, and the reception of the system transceiver S2 is seriously interfered; or, the system transceiver S2 The signal is transmitted to UE-2, and the system transceiver SI receives the signal from UE-1, and the reception of system transceiver S1 will be seriously interfered.

Second, UE 1 transmits a signal, UE-2 receives a signal, and UE 2 receives severe interference; or UE-2 transmits a signal, UE-1 receives a signal, and UE-1 receives 1 and is severely interfered.

Third, the system transceiver S1 and the system transceiver S2 simultaneously transmit signals, and there is interference between the reception of the UE-1 and the reception of the UE 2.

Fourth: UE-1 and UE-2 transmit signals at the same time, and there is interference between the reception of the system transceiver S1 and the reception of the system transceiver S2.

Among the above four types of interference, in the first type of interference, the transmitting signal of the system transceiver S1 and the receiving signal of the system transceiver S2 are adjacent to each other, or the transmitting signal of the system transceiver S2 and the receiving signal of the system transceiver S2 are adjacent to each other. , so that the transmitted signal will have energy leakage into the frequency band of the received signal, coupled with the system transceiver S1/system transceiver S2 co-site common site, the interference signal strength will be very large, the interference is the most serious, must use the protection of the isolation zone The way can be eliminated, and the second, third and fourth kinds of interference can be solved by formulating a reasonable transmitter out-of-band leakage indicator and receiver adjacent frequency suppression index. For example, it can be solved by establishing a reasonable ACLR (Adjacent Channel Leakage Ratio) and receiver adjacent channel selectivity (ACS, AdjacentChannel Selectivity). Summary of the invention

In view of this, the main object of the present invention is to provide a method and system for eliminating adjacent frequency interference to solve the problem of waste of resources caused by the need to establish a protection isolation band in the existing adjacent frequency interference.

In order to achieve the above object, the technical solution of the present invention is achieved as follows:

The present invention provides a method for canceling adjacent frequency interference, the method comprising: acquiring related information of an adjacent frequency downlink signal, and obtaining an interference signal; and canceling the interference signal from the received uplink signal. In the above solution, the acquiring the related information of the downlink downlink signal includes: transmitting, by the first system transceiver for transmitting the downlink signal, related information of the downlink signal to the second system transceiver, so that the second The system transceiver obtains information about the downlink signal of the adjacent frequency.

In the above solution, the information about the downlink signal is notified to the second system transceiver, where: the first system transceiver notifies the related information of the downlink signal to the device by means of wired transmission. The second system transceiver.

In the above solution, the notifying the information about the downlink signal to the second system transceiver includes: notifying, to the second system transceiver, frequency band information or subcarrier information of all downlink signals; or And notifying, to the second system transceiver, frequency band information or subcarrier information of a part of the downlink signal adjacent to the adjacent frequency band.

In the above solution, the part of the downlink signal that is adjacent to the adjacent frequency band is: a part of the signal in the preset frequency band with the adjacent frequency band as a boundary, or the carrier frequency of the adjacent frequency band The subcarriers count up a portion of the signals of a preset number of subcarriers.

In the above solution, the obtaining the interference signal includes: performing signal recovery according to the related information of the acquired downlink downlink signal, to obtain an interference signal.

In the above solution, the performing signal recovery includes: when the downlink signal is an orthogonal frequency division multiple access (OFDMA) signal, performing signal recovery by using an OFDMA modulation method.

The present invention also provides a system for eliminating adjacent-channel interference, the system comprising: a second system transceiver, the second system transceiver includes an acquisition unit, a receiving unit, and a cancellation unit, wherein the acquisition unit is configured to acquire The related information of the downlink signal of the adjacent frequency, and the interference signal is obtained; the receiving unit is configured to receive the uplink signal;

And an eliminating unit, configured to cancel the interference signal obtained by the acquiring unit from the uplink signal received by the receiving unit.

In the above solution, the system further includes: a first system transceiver, configured to transmit the And a line signal, and notifying the second system transceiver of the information about the downlink signal.

In the above solution, the first system transceiver and the second system transceiver are connected by wire;

The first system transceiver is configured to notify related information of the downlink signal to the second system transceiver by means of wired transmission.

In the above solution, the first system transceiver is a system transceiver of a frequency division duplex (FDD) system or a time division duplex (TDD) system; and/or, the second system transceiver is an FDD system or a TDD System system transceiver.

In the invention, the interference signal is obtained by acquiring the related information of the downlink signal of the adjacent frequency, so that the interference signal can be directly eliminated in the received uplink signal, and the adjacent channel interference of the receiving end is eliminated, and the adjacent frequency is not needed. The establishment of a protection isolation zone saves spectrum resources, avoids waste of spectrum resources, and enables spectrum resources to be fully utilized and improved spectrum utilization. DRAWINGS

1 is a flowchart of an implementation of a method for eliminating adjacent frequency interference according to the present invention;

2 is a schematic diagram of the adjacent signal interference caused by the downlink signal Slt(t) on the uplink signal S2r(t) according to the first embodiment of the present invention;

FIG. 3 is a schematic diagram of an interference signal SI according to Embodiment 1 of the present invention. detailed description

The basic idea of the present invention is: for a communication system in which two adjacent frequencies coexist, the system transceiver receiving the uplink signal acquires information about a downlink signal adjacent to the uplink signal, and determines the information based on the downlink signal. Interfering with the signal and removing the interfering signal from the upstream signal. In this way, it is not necessary to set up a protection isolation band, which can eliminate adjacent frequency interference, save frequency band resources, and improve spectrum utilization. The method for eliminating the adjacent-frequency interference of the present invention, as shown in FIG. 1 , may mainly include the following steps: Step 101: Acquire relevant information of a downlink downlink signal, and obtain an interference signal;

Here, the related information of the downlink signal may be information indicating the characteristics of the downlink signal, such as frequency band information of the downlink signal, or subcarrier information, and the like.

Specifically, the first system transceiver for transmitting the downlink signal notifies the information about the downlink signal to the second system transceiver, so that the second system transceiver acquires related information of the downlink downlink signal.

Here, the first system transceiver may notify the information about the downlink signal to the second system transceiver before transmitting the downlink signal, or transmitting the downlink signal, or after transmitting the downlink signal.

The first system transceiver may notify related information of the downlink signal to the second system transceiver by means of wired transmission. In a practical application, the first system transceiver may be connected to the second system transceiver by a wired connection, for example, through a local transmission interface or through a cable (such as a network cable, etc.), so that the first system transceiver The related information of the downlink signal may be notified to the second system transceiver through a local transmission interface or a cable.

The notifying the information about the downlink signal to the second system transceiver may include: notifying, to the second system transceiver, frequency band information or subcarrier information of all downlink signals; or The band information or subcarrier information of a portion of the signal in the vicinity of the adjacent band is notified to the second system transceiver.

Here, the partial signal of the downlink signal adjacent to the adjacent frequency band is: a part of the signal in the preset frequency band with the adjacent frequency band as a boundary in the downlink signal, or a sub-band with the adjacent frequency band as a carrier frequency The carrier counts up a part of the signal of a preset number of subcarriers.

Step 102: Eliminate the interference signal from the received uplink signal.

Specifically, according to the obtained information about the downlink signal of the adjacent frequency, the signal is recovered, and To the interference signal. The second system transceiver may perform signal recovery according to the signal modulation method of the downlink signal according to the obtained information about the downlink signal of the adjacent frequency to obtain an interference signal. For example, when the downlink signal is an Orthogonal Frequency Division Multiple Access (OFDMA) signal, the signal recovery is performed by using an OFDMA modulation method.

Correspondingly, the present invention further provides a system for eliminating adjacent frequency interference, the system comprising: a second system transceiver, the second system transceiver includes an acquisition unit, a receiving unit, and a cancellation unit, wherein the acquisition unit, The information about the downlink signal of the adjacent frequency is obtained, and the interference signal is obtained, and the receiving unit is configured to receive the uplink signal, and the canceling unit is configured to: receive the uplink signal received by the acquiring unit from the receiving unit Eliminated in.

The system further includes: a first system transceiver, configured to transmit the downlink signal, and notify related information of the downlink signal to the second system transceiver.

The first system transceiver is connected to the second system transceiver by a wired connection; the first system transceiver is further configured to notify the second information about the downlink signal by means of wired transmission. System transceiver.

In practical applications, the first system transceiver and the second system transceiver are co-site or geographically close, and adjacent to each other.

Preferably, the first system transceiver may be a system transceiver of an FDD system or a system transceiver of a TDD system, and the second transceiver may also be a system transceiver of an FDD system or a system transceiver of a TDD system.

Embodiment 1

In this embodiment, an LTE communication system with two bandwidths of 20 MHz in the 2.6G frequency band is used as an example to describe the specific process of eliminating adjacent frequency interference for a communication system in which two adjacent frequencies coexist.

In this embodiment, the communication systems in which two adjacent frequencies coexist are the LTE TDD system C1 and the LTE FDD system C2, wherein the LTE TDD system C1 includes the system transceiver S1 and the terminal transceiver UE 1 , and the LTE FDD system C2 includes the system transceiver. Machine S2 and terminal transceiver UE 2, system receiving The sender SI and the system transceiver S2 share the site,

The 2.6 GHz band is divided into: FDD uplink band from 2500 MHz to 2570 MHz and FDD downlink band from 2620 MHz to 2690 MHz. As shown in FIG. 2, in this embodiment, the downlink signal Slt(t) of the system transceiver S1 is a signal with a center carrier frequency of 2630 MHz and a bandwidth of 20 MHz, and the uplink signal S2r(t) of the system transceiver S2 is 2610 MHz. For the center carrier frequency and the bandwidth of 20MHz, the upper limit of the frequency band of the downlink signal Slt(t) of the system transceiver S1 is 2620MHz, and the lower limit of the frequency band of the uplink signal S2r(t) of the system transceiver S2 is 2620MHz. Therefore, the system transceiver The downlink signal Slt(t) of S1 is in close proximity to the uplink signal S2r(t) of the system transceiver S2. At 2620 MHz, part of the energy of the downlink signal Slt(t) of the system transceiver S1 is leaked into the uplink signal S2r of the system transceiver S2. (t), thereby causing interference to the uplink signal S2r(t) of the system transceiver S2, and the system transceiver S1 downlink signal Slt(t) has the strongest interference to the uplink signal S2r(t) of the system transceiver S2.

The specific implementation process for eliminating the above interference may mainly include the following steps:

Step 1: The system transceiver S1 informs the system transceiver S2 of the downlink signal Slt(t) through the local transmission interface;

Here, the local transmission interface may be a dedicated interface for interaction information between the system transceiver S1 and the system transceiver S2.

Specifically, the system transceiver S1 notifies the system transceiver S2 of the information about the downlink signal Slt(t), which can be implemented in the following two ways:

First, the system transceiver S1 can notify the system transceiver S2 of the frequency band information or subcarrier information of all the downlink signals Slt(t), so that the system transceiver S2 can according to the center carrier frequency, bandwidth, etc. of the downlink signal Slt(t). The information recovers the downlink signal Slt(t), determines that the downlink signal Slt(t) is the interference signal SI, and eliminates the partial downlink signal Slt(t) included in the uplink signal S2r(t).

Second, the system transceiver S1 can notify the system transceiver S2 of the frequency band information or subcarrier information of the partial downlink signal Slt(t) adjacent to the adjacent frequency band, so that the system transceiver S2 can be based on the department. The partial downlink signal Slt(t) is recovered by the information of the carrier frequency and the bandwidth of the downlink signal Slt(t). The partial downlink signal Slt(t) is the interference signal SI, and the uplink signal S2r(t) is included. The interference signal SI is eliminated.

Here, the partial downlink signal Slt(t) adjacent to the adjacent frequency band is a partial signal in a preset frequency band in the downlink signal Slt(t), or may be a portion in the downlink signal Slt(t) where the distance adjacent frequency band is a preset bandwidth. The signal, the frequency band information may be preset frequency band information, or may be the preset bandwidth, and may be set according to actual application requirements. For example, when the adjacent frequency band is 2620 MHz, the preset frequency band may be 2620 MHz to 2622 MHz, and the preset bandwidth may be 2 MHz. At this time, the partial downlink signal Slt(t) is a signal with a frequency band between 2620 MHz and 2622 MHz.

For LTE, the downlink signal Slt(t) is an OFDMA signal, and the system transceiver S1 can notify the system transceiver S2 of the information of consecutive X subcarriers in the downlink signal Slt(t) adjacent to the adjacent frequency band, where the number of subcarriers X can be set according to the performance and complexity of the implementation. The value of X ranges from 1 to the maximum number of subcarriers of the system transceiver S1. When X is the maximum number of subcarriers of the system transceiver S1, it means that the system transmits and receives. The machine S1 notifies the system transceiver S2 of the subcarrier information of all the downlink signals Slt(t). For example, when X is set to 5, the system transceiver S1 notifies the system transceiver S2 of the continuous five subcarrier information scl, sc2, sc3, sc4, and sc5 from the number of subcarriers having a carrier frequency of 2620 MHz, and simultaneously downlinks The transmission time of the signal Slt(t) is notified to the system transceiver S2.

Step 2: After receiving the information about the downlink signal Slt(t) that has the strongest interference to its neighbor frequency, the system transceiver S2 performs signal recovery locally to obtain the interference signal SI, and the interference signal SI is from the uplink signal S2r(t). In the middle, the uplink signal S2r0 (t) without adjacent frequency interference is obtained, and thus, the elimination of the adjacent frequency interference of the FDD downlink signal to the TDD uplink signal in the 2500 MHz band is realized.

Specifically, as shown in FIG. 3, the system transceiver S2 performs local signal recovery to obtain the interference signal SI according to the correlation information of the downlink signal Slt(t) according to the modulation method of the downlink signal Slt(t), that is, the OFDMA modulation method. When the system transceiver S2 receives the uplink signal S2r(t) sent by the UE-2, The interference signal SI in the uplink signal S2r(t) is cancelled to obtain an uplink signal S2r0 (t)=S2r(t)-SI without adjacent frequency interference.

Here, the OFDMA modulation method is a known prior art and is clearly described in detail in industry standards such as the 3GPP (Third Generation Partnership Projects) technical specification 36.211 (TS36.211).

For the same reason, the foregoing method can also be used to eliminate the adjacent-frequency interference of the TDD downlink signal to the FDD uplink signal, and the specific implementation process is the same as that in the foregoing embodiment 1, and details are not described herein again.

The above is only the preferred embodiment of the present invention and is not intended to limit the scope of the present invention.

Claims

Claim

A method for eliminating adjacent frequency interference, characterized in that the method comprises:

Obtaining related information of the downlink signal of the adjacent frequency, and obtaining an interference signal;

The interference signal is cancelled from the received uplink signal.

The method for canceling adjacent channel interference according to claim 1, wherein the acquiring information about the downlink signal of the adjacent frequency includes:

The first system transceiver for transmitting the downlink signal notifies the information about the downlink signal to the second system transceiver, so that the second system transceiver acquires related information of the downlink downlink signal.

The method for canceling adjacent frequency interference according to claim 2, wherein the notifying the related information of the downlink signal to the second system transceiver is:

The first system transceiver notifies the information about the downlink signal to the second system transceiver by means of wired transmission.

The method for canceling adjacent frequency interference according to claim 2 or 3, wherein the notifying the related information of the downlink signal to the second system transceiver comprises: frequency band information of all downlink signals Or notifying the second system transceiver of the subcarrier information; or notifying the second system transceiver of the frequency band information or the subcarrier information of the part of the downlink signal that is adjacent to the adjacent frequency band.

The method for canceling adjacent-channel interference according to claim 4, wherein a part of the downlink signal adjacent to the adjacent frequency band is: a preset frequency band in the downlink signal with the adjacent frequency band as a boundary a partial signal, or a partial signal of a preset number of subcarriers counted by using the subcarriers with the adjacent frequency band as the carrier frequency.

The method for canceling adjacent frequency interference according to claim 1, 2, or 3, wherein the obtaining the interference signal comprises: performing signal recovery according to the obtained related information of the adjacent downlink downlink signal, and obtaining interference signal.

The method for canceling adjacent frequency interference according to claim 6, wherein the performing signal recovery comprises: when the downlink signal is an orthogonal frequency division multiple access (OFDMA) signal, using an OFDMA modulation method to perform signal restore.

A system for eliminating adjacent-channel interference, wherein the system includes: a second system transceiver, the second system transceiver includes an acquiring unit, a receiving unit, and a canceling unit, wherein the acquiring unit is configured to: Obtaining related information of the downlink signal of the adjacent frequency, and obtaining an interference signal; and receiving unit, configured to receive the uplink signal;

The system for canceling adjacent frequency interference according to claim 8, wherein the system further comprises: a first system transceiver, configured to transmit the downlink signal, and notify relevant information of the downlink signal to The second system transceiver.

10. The system for eliminating adjacent frequency interference according to claim 9, wherein the first system transceiver and the second system transceiver are connected by wire;

The system for eliminating adjacent frequency interference according to any one of claims 8 to 10, wherein the first system transceiver is a system of a frequency division duplex (FDD) system or a time division duplex (TDD) system. a transceiver; and/or, the second system transceiver is a system transceiver of an FDD system or a TDD system.