WO2009003312A1

WO2009003312A1 - A method for automatically selecting the relay mode in relay station in wireless relay network and a device thereof

Info

Publication number: WO2009003312A1
Application number: PCT/CN2007/002047
Authority: WO
Inventors: Keying Wu
Original assignee: Alcatel Shanghai Bell Company, Ltd.
Priority date: 2007-06-29
Filing date: 2007-06-29
Publication date: 2009-01-08

Abstract

A method for controlling the signal relay in a relay station in wireless relay network and a device thereof are provided in the invention, the relay station first detects the signal quality of the signal from an anterior device, and generates the signal quality relate information (S11); then, on the basis of the signal quality relate information, selects a corresponding relay work mode to relay the signal from the anterior device (S12). The method of the present invention combines the advantage of the two relay work modes in the prior art, and has preferable adaptability in different application scenes. The technique scheme can be combined with Hybrid Auto Retransmission Request (HARQ) and cooperation relay technique easily, and can realize the time and space diversity gain totally.

Description

Method and device for automatically selecting relay mode in relay station of wireless relay network

The present invention relates to a wireless relay network, and more particularly to a relay station in a wireless relay network. Background technique

In wireless communication systems, in order to extend and extend the coverage of a wireless network, one or more relay stations are typically used throughout the wireless communication network to forward signals from higher level devices.

In a relay-based wireless communication network system, a relay station usually has two modes of operation: the first relay operation mode is an amplification forward (A&F) relay operation mode, and the second relay operation mode is a decoding forward direction ( D&F) Relay mode of operation. For the amplification forward (A&F) relay mode, each relay only amplifies and forwards the received signal from the upper device; for the decoding forward (D&F) relay mode, each relay pair receives The signal from the higher-level device is decoded, re-encoded, and then forwarded. 1 shows a schematic diagram of a network structure of a relay-based wireless communication network according to the prior art. In Figure 1, the relay station first receives the signal from the source device; then, processes the received signal from the source device according to the corresponding relay working mode; finally, forwards the processed signal to the destination device. It will be understood by those skilled in the art that although only one relay station is shown in Fig. 1, there may be multiple relay stations in a specific application to forward signals from the upper level device. The relay station in Figure 1 can use the amplified forward (A&F) relay working mode to amplify and forward the received source device signal, or use the decoding forward (D&F) relay working mode to receive the received from the upper The signals of the primary device are decoded, re-encoded, and then forwarded. Once the relay's relay mode of operation is determined, it will not change during the entire signal transmission.

The two relay working modes in the prior art have their own advantages and disadvantages: The first type of amplification forward (A&F) relay working mode has the advantages of simple processing and low power consumption, but the relay working mode is zoomed in. At the same time as the message signal, the noise signal is also amplified, so it has a problem of noise propagation. Decoding Forward (D&F) relay mode of operation, although before forwarding the message

1

Confirmation Additional noise is removed, but this process comes at the cost of high processing complexity and high power consumption. In addition, the decoding forward (D&F) relay working mode also has the problem of error propagation, that is, the decoding error of the relay station will spread. To the terminal or the next relay station. Summary of the invention

In order to solve the above-mentioned drawbacks in the prior art, the present invention proposes a method and apparatus for controlling the operation mode of a relay station in a relay station of a wireless relay network.

According to an aspect of the present invention, a method for controlling a relay of a signal in a relay station of a wireless relay network is provided, comprising the steps of: i. detecting a signal of a signal from a higher-level device Quality to generate signal quality related information; ii. According to the signal quality related information, select a corresponding relay working mode to relay the signal from the upper level device.

According to still another aspect of the present invention, a device for controlling a relay of a signal in a relay station of a wireless relay network is provided, including: a first detecting device, configured to detect a device from a higher level The signal quality of the signal is generated to generate signal quality related information; the first selecting means is configured to select a corresponding relay working mode to relay the signal from the upper level device according to the signal quality related information.

The technical solution proposed by the present invention combines the advantages of the two relay working modes in the prior art, and has strong flexibility in different application scenarios. This solution is also very easy to combine with Hybrid Automatic Repeat Request (HARQ) and cooperative relay technology to fully realize time and space diversity gain. DRAWINGS

Other features, objects, and advantages of the present invention will become more apparent from the detailed description of the accompanying drawings.

1 is a schematic diagram showing a network structure of a relay-based wireless communication network according to the prior art;

2 shows a flow chart of a method for controlling relaying of signals in a relay station of a wireless relay network, in accordance with an embodiment of the present invention; FIG. 3 illustrates a flow of a method for controlling a relay of a signal in a relay station of a wireless relay network when the signal quality related information includes a signal to noise ratio or a signal strength according to an embodiment of the present invention. Figure

4 is a flowchart showing a method for controlling a relay of a signal in a relay station of a wireless relay network when the signal quality related information includes a code check result according to an embodiment of the present invention;

FIG. 5 illustrates a control device for controlling a relay of a signal in a relay station of a wireless relay network when the signal quality related information includes a signal to noise ratio or a signal strength according to an embodiment of the present invention. Schematic;

6 is a schematic structural diagram of a control device for controlling a relay of a signal in a relay station of a wireless relay network, when the signal quality related information includes a code check result according to an embodiment of the present invention. ; as well as

Fig. 7 shows a schematic diagram of a specific implementation for controlling selective relaying of signals according to the present invention in a relay station of an Orthogonal Frequency Division Multiple Access (OFDMA) system. detailed description

The invention is described in detail below with reference to the accompanying drawings:

2 shows a flow chart of a method for controlling relaying of signals in a relay station of a wireless relay network, in accordance with an embodiment of the present invention;

In this embodiment, step S11 is first performed, and the relay station detects the signal quality of the signal from the upper-level device to generate signal quality-related information;

Secondly, in step S12, according to the signal quality related information, a corresponding relay working mode is selected to relay the signal from the upper level device.

The upper-level device involved in steps S11 and S12 may be a source device or a relay station. Those skilled in the art can understand that when the wireless relay network only includes one relay station, the relay station directly receives the signal from the source device, and then detects the signal quality of the signal from the source device to generate a signal shield. Quantity related information; when the wireless relay network includes more than one relay station, the relay station receives The signal may be from the source device or from the upper-level relay station, depending on the location of the relay station in the wireless relay network, which is well known to those skilled in the art, and will not be described herein; The signal quality of the signal forwarded from the source device/upper relay station is detected to generate signal quality related information.

Specifically, in the present embodiment, the signal quality related information may include various forms such as a signal to noise ratio or a signal strength, or a code check result. It should be understood by those skilled in the art that the signal quality related information may also include other forms as long as the relay station can select an appropriate relay working mode according to the signal quality related information, which is not described herein.

FIG. 3 illustrates a flow of a method for controlling a relay of a signal in a relay station of a wireless relay network when the signal quality related information includes a signal to noise ratio or a signal strength according to an embodiment of the present invention. Figure.

In this embodiment, step S21 is first performed to detect a signal to noise ratio or a signal strength of the signal from the upper level device to generate a signal to noise ratio value or a signal strength value of the signal from the upper level device. ;

Next, step S22 is performed to compare the signal to noise ratio value or the signal strength value of the signal from the upper level device with a predetermined threshold;

Step S23 is performed again to determine whether the signal to noise ratio value or the signal strength value is greater than a predetermined threshold;

If the signal to noise ratio value or the signal strength value is greater than the predetermined threshold, step S24 is performed to select a decoding forward relay working mode to relay the signal from the upper level device;

If the signal to noise ratio value or the signal strength value is less than the predetermined threshold, step S25 is performed to select the amplification forward relay operation mode to relay the signal from the upper level device.

Specifically, when the relay station selects to decode the forward relay working mode, the relay station decodes, re-encodes the received signal from the upper-level device, and then forwards the signal; when the relay station selects the forward direction In the relay working mode, the relay station directly amplifies and forwards the received signal from the upper-level device.

Specifically, when the signal to noise ratio value or the signal strength value of the signal from the upper level device is greater than a predetermined threshold value, it may be considered that the relay station works by using the decoding forward relay. When the mode relays the signal, the probability of a decoding error occurring will be very small, so that the decoding can be assumed to be correct.

Specifically, the predetermined threshold depends on the modulation mode and channel coding mode used, wherein the higher the code rate of the code used, the higher the predetermined threshold. Further, the predetermined threshold may be calculated offline by Monte Carlo simulation in advance.

In the preferred embodiment where the signal quality related information described above includes signal to noise ratio or signal strength, the method achieves a good trade-off between complexity and performance, since the relay station always selects the most based on the current channel conditions. Excellent working mode, and the received information is decoded only when needed. A disadvantage of this approach is that signal-to-noise ratio or signal strength detection is not a very accurate method for predicting decoding results. When the signal-to-noise ratio or signal strength of the detected 'j' exceeds a predetermined threshold, decoding errors may still occur, and therefore, error propagation cannot be completely avoided.

4 is a flow chart showing a method for controlling a relay of a signal in a relay station of a wireless relay network when the signal quality related information includes a code check result according to an embodiment of the present invention.

In this embodiment, step S31 is first performed to decode the signal from the upper-level device to generate a decoded signal.

Next, step S32 is performed to perform code verification on the decoded signal to generate a code check result;

Step S33 is performed again to determine whether the code verification result is correct.

If the code check result is correct, step S34 is performed to select a decoding forward relay mode to relay the signal from the upper device;

If the verification result is an error, step S35 is performed to select an amplification forward (A&F) relay operation mode to relay the signal from the upper level device.

Preferably, the code check may comprise a cyclic redundancy check or a parity check. Skill A person skilled in the art can understand that the code check can also include other forms of code check, as long as the relay station can select an appropriate relay working mode according to the code check result, and details are not described herein.

Specifically, when a cyclic redundancy code (CRC) check is used, the source device and the relay station use the same generator polynomial g ( X ), and the coefficients of the first and last bits of g ( x ) must be 1. The specific processing method is as follows: the source device removes t ( x ) by g ( X ) , and obtains a remainder as a cyclic redundancy check code, where t ( X ) is the binary data to be sent; when the relay station decodes, it is received The data is removed g ( X ), if the remainder is zero; it means there is no error in the transmission process; if the remainder is not zero, there is an error in the transmission process. Further, CRC-4, CRC-16, CRC-32 test can be used, where "4", "16", "32" represent the order of the generator polynomial g(X), and the order of the generator polynomial of the CRC is more High, the probability of misjudgment is smaller.

Specifically, the parity code is an odd or even number encoding method by adding redundant bits so that the number of "1"s in the code word is an error detection code. In actual use, it can be divided into vertical parity, horizontal parity, and horizontal and vertical parity.

In the preferred embodiment in which the signal quality related information described above includes a code check result, the method effectively prevents error propagation, but is complicated to implement because full decoding is required in any case.

FIG. 5 illustrates a control device for controlling a relay of a signal in a relay station of a wireless relay network when the signal quality related information includes a signal to noise ratio or a signal strength according to an embodiment of the present invention. Schematic. The control device 1 includes a signal detecting device 11 and a selection relay device 12.

First, the signal detecting device 11 is configured to detect a signal quality of a signal from a higher-level device to generate signal quality-related information;

Next, the relay device 12 is selected to select a corresponding relay working mode to relay the signal from the upper device according to the signal quality related information.

The upper level device involved in the devices 11, 12 may be a source device or a relay station. Those skilled in the art can understand that when the wireless relay network only includes one relay station, the relay station directly receives the signal from the source device, and then the The signal quality of the signal of the source device is detected to generate signal quality related information; when the wireless relay network includes more than one relay station, the signal received by the relay station may be from the source device or may be from the upper relay station. Forwarded signal, depending on the location of the relay station in the wireless relay network, and then detecting the signal quality of the signal forwarded from the source device/upper relay station to generate signal quality related information, which The substance of the invention is not affected.

Specifically, in the present embodiment, when the signal quality related information includes a signal to noise ratio or a signal strength, the selection relay device 12 includes a signal comparison device 121 and a first selection device 122. More specifically, the signal detecting device 11 is configured to detect a signal to noise ratio or a signal strength of the signal from the upper level device to generate a signal to noise ratio value or a signal strength value of the signal from the upper level device. The signal comparing means 121 is configured to compare the signal to noise ratio value or the signal strength value of the signal from the upper level device with a predetermined threshold to generate a comparison result; the first selecting means 122 is configured to The comparison result performs the following operations: if the signal to noise ratio value or the signal strength value is greater than the predetermined threshold, selecting a decoding forward relay working mode to relay the signal from the upper level device; The noise ratio value or the signal strength value is less than the predetermined threshold, and is used to select an amplification forward relay operation mode to relay the signal from the upper-level device.

Specifically, when the signal to noise ratio value or the signal strength value of the signal from the upper level device is greater than a predetermined threshold, it may be considered that the relay station decodes the error when using the decoding forward relay working mode to relay the signal. The probability of occurrence will be very small, so that the decoding can be assumed to be correct.

Specifically, the threshold threshold depends on the modulation mode and channel coding mode used, wherein the higher the code rate of the code used, the higher the threshold threshold. Further, the threshold threshold may be calculated offline by Monte Carlo simulation in advance.

The signal quality related information described above includes a signal to noise ratio or a signal strength. In the embodiment, the control device achieves a good trade-off between the complexity and performance of the system, because the relay station always selects the optimal working mode according to the current channel condition, and only receives the received mode when needed. The information is decoded. A disadvantage of this control device is that signal to noise ratio or signal strength detection is not a very accurate method for predicting decoding results. When the detected signal-to-noise ratio or signal strength exceeds a predetermined threshold, decoding errors may still occur, and therefore, error propagation cannot be completely avoided.

6 is a schematic structural diagram of a control device for controlling a relay of a signal in a relay station of a wireless relay network, when the signal quality related information includes a code check result according to an embodiment of the present invention. . The control device Γ includes a signal detecting device 11, and a relay device 12 is selected.

First, the signal detecting device 11 is configured to detect a signal quality of a signal from a higher-level device to generate signal quality related information;

Specifically, in the present embodiment, when the signal quality related information includes a code check result, the signal detecting device 11 includes a decoding device 11 and a code check device 112, and the relay device 12 is selected, including the second option. Device 121,. More specifically, the decoding device 111 is configured to decode the signal from the upper-level device to generate a decoded signal, and the code verification device 112 is configured to perform code verification on the decoded signal. Generating a code check result; the second selecting means 121 is configured to perform the following operations according to the code check result: if the code check result is correct, selecting a decoding forward relay working mode to relay the incoming a signal of the upper level device; if the code check result is an error, the first selecting means is configured to select an amplification forward (A&F) relay working mode to relay the signal from the upper level device.

Preferably, the code check may include a cyclic redundancy code face or parity. Skill A person skilled in the art can understand that the code check can also include other forms of code check, as long as the relay station can select an appropriate relay working mode according to the code check result, and details are not described herein.

Specifically, when using Cyclic Redundancy Code (CRC) check, the source device and the relay station use the same generator polynomial g (x), and the coefficients of the first and last bits of g (x) must be 1. The specific processing method is as follows: the source device removes t ( X ) by g ( X ), and obtains a remainder as a cyclic redundancy check code, where t ( X) is the binary data to be transmitted; when the relay station decodes, it is received The data is removed g ( X ), if the remainder is zero; it means there is no error in the transmission process; if the remainder is not zero, there is an error in the transmission process. Further, CRC-4, CRC-16, CRC-32 test can be used, where "4", "16", "32" represent the order of the generator polynomial g ( X ), and the order of the generator polynomial of the CRC is more High, the probability of misjudgment is smaller.

In the preferred embodiment in which the signal quality related information described above includes a code check result, the control device effectively prevents error propagation, but is complicated to implement because full decoding is required in any case.

Figure 7 is a block diagram showing the construction of a specific implementation for controlling selective relaying of signals in accordance with the present invention in a relay station of an Orthogonal Frequency Division Multiple Access (OFDMA) system.

In an Orthogonal Frequency Division Multiple Access (OFDMA) system, information of different users and other information (e.g., connection identifier CID) are combined into one OFDM symbol through different subcarriers. This information may require different processing in the relay station. For example, the connection identification CID information needs to be extracted and completely decoded in any case; and the information of different users is different through the different channels in the transmission process, so that the quality of the information received by the different users is not the same, so The received signals are processed using different relay operating modes.

Specifically, FIG. 7 includes a fast Fourier transformer 21, a user signal separator 22, The signal quality detector 23, the relay operating mode selector 24, the signal processor 25, the user signal combiner 26, and the fast Fourier inverse transformer 27.

The fast Fourier transformer 21 is configured to perform Fourier transform on the received signal, and transform the received time domain signal into the frequency domain to generate a Fourier transformed signal user signal separator 22 for configuring the subcarrier according to the configuration. Separating the Fourier transformed different user information and other information (eg, connection identifier CID) to generate a plurality of user signals separated by the user signal separator;

The signal quality detector 23 is configured to detect signal quality of a plurality of user signals separated by a user signal separator to generate signal quality related information;

The relay working mode selector 24 is configured to select a corresponding relay working mode according to the signal quality related information;

The signal processor 25 is configured to process the plurality of user signals separated by the user signal separator according to the selected relay working mode to generate a plurality of user signals processed by the signal processor;

The user signal combiner 26 is configured to combine the plurality of user signals processed by the signal processor to generate a combined signal by the user signal combiner;

The fast Fourier inverse transformer 27 is configured to perform inverse fast Fourier transform on the signal combined by the user signal combiner to generate a fast Fourier inversely transformed signal, and then forward the fast Fourier inversely transformed signal.

Specifically, the signal quality detector 23 is equivalent to the signal detecting device 11 shown in FIG. 5 or the signal detecting device 11 shown in FIG. 6, which detects the signal quality of a plurality of user signals separated by the user signal separator, The signal quality related information is generated; the relay working mode selector 24 is equivalent to the selective relay device 12 shown in FIG. 5 or the selective relay device 12 shown in FIG. 6, which selects the relay working mode according to the signal quality related information. . The relay working mode selector 24 may select to decode the forward relay working mode, or may select to amplify the forward relay working mode. When the relay operation mode selector 24 selects the decoding forward relay operation mode, the signal processor 25 decodes, re-encodes, and then forwards the received plurality of user signals separated by the user signal separator; Working mode selector 24 Selecting the forward forward relay mode of operation, the signal processor 25 directly amplifies and forwards the received plurality of user signals separated by the user signal separator.

More specifically, the signal quality related information generated by the signal quality detector 23 may include various forms such as a signal to noise ratio or signal strength, or a code check result. It should be understood by those skilled in the art that the signal quality related information may also include other forms, as long as the relay station can select an appropriate relay working mode according to the signal quality related information, and details are not described herein.

Further, when the signal quality related information includes a signal to noise ratio or a signal strength, the signal quality detector 23 is equivalent to the signal detecting device 11 shown in FIG. 5 for detecting the received separation by the user signal separator. a signal-to-noise ratio or signal strength of the plurality of user signals to generate a signal-to-noise ratio value or a signal strength value of the received plurality of user signals separated by the user signal separator; and the relay working mode selector 24 is equivalent to the selective relay device 12 shown in FIG. 5, which includes a signal comparing device 121 and a first selecting device 122 for using the received plurality of users separated by the user signal separator. The signal to noise ratio value or signal strength value of the signal is compared to a predetermined interpretation value to generate a comparison result; the first selection means 122 is configured to perform the following operations for the comparison result: if the signal to noise ratio value or signal strength value is greater than Determining, by the predetermined threshold, a decoding forward relay operation mode to relay the received plurality of user signals separated by the user signal separator; SNR or signal strength value is less than the predetermined threshold value, a plurality of user selection signals before amplifying the relay mode of operation to relay the signal received via the user splitter for separation is selected.

Further, when the signal quality related information includes a code check result, the signal quality detector 23 is equivalent to the signal detecting device 1 shown in FIG. 6, which includes the decoding device 111, and the code check device 112, for simplicity. For the sake of illustration, the decoding device 111, and the code checking device 112, not shown in FIG. 7, and the relay operating mode selector 24 is identical to the selective relay device 12 shown in FIG. 6, which includes the second selecting device 12A, For the sake of simplicity, the second selection means 121 is not shown in FIG. The decoding device 111 is configured to decode the signal from the upper-level device to generate a decoded signal, and the code verification device 112 is configured to perform code verification on the decoded signal to generate Code check result; the second selection The device 121 is configured to perform the following operations according to the code check result: if the code check result is correct, selecting a decoding forward relay working mode to relay the signal from the upper device; The code check flag is an error, and the first selection device is configured to select an amplification forward (A&F) relay operation mode to relay the signal from the upper device.

The present invention has been described with respect to the specific embodiments thereof, and it is understood that the present invention is not limited to the specific embodiments described above, and those skilled in the art can make various modifications and changes within the scope of the appended claims.

Claims

Claim 1 - A method for controlling a relay of a signal in a relay station of a wireless relay network, comprising the steps of:

1. Detecting the signal quality of the signal from the higher-level device to generate signal quality related information;

Ii. Select a corresponding relay working mode to relay the signal from the upper device according to the signal quality related information.

2. The method according to claim 1, wherein the signal quality related information comprises a signal to noise ratio or a signal strength, and step i comprises the following steps:

a. detecting a signal to noise ratio or signal strength of the signal from the upper level device to generate a signal to noise ratio value or a signal strength value of the signal from the upper level device.

3. The method according to claim 2, wherein step ii comprises the following steps:

b. comparing the signal to noise ratio value or the signal strength value of the signal from the upper level device with a predetermined threshold;

- if the signal to noise ratio value or signal strength value is greater than a predetermined threshold, selecting a decoding forward relay mode of operation to relay the signal from the upper level device;

- if the signal to noise ratio value or signal strength value is less than a predetermined threshold, then selecting a forward forward relay mode of operation to relay the signal from the higher level device.

The method according to claim 1, wherein the signal quality related information comprises a code check result, and the step i comprises the following steps:

A. decoding the signal from the upper level device to generate a decoded signal;

B. Perform code verification on the decoded signal to generate a code check result.

5. The method according to claim 4, wherein step ii comprises the following steps:

- if the code check result is correct, selecting a decoding forward relay working mode to relay the signal from the upper level device; - If the verification result is an error, the amplification forward (A&F) relay operation mode is selected to relay the signal from the upper device.

The method according to claim 4 or 5, wherein the code check comprises a cyclic redundancy code check or a parity check.

A control device for controlling a relay of a signal in a relay station of a wireless relay network, comprising:

a signal detecting device, configured to detect a signal quality of a signal from a higher-level device to generate signal quality related information;

And selecting a relay device, configured to select a corresponding relay working mode to relay the signal from the upper device according to the signal quality related information.

8. The control device according to claim 7, wherein the signal quality related information comprises a signal to noise ratio or a signal strength.

The signal detecting device is further configured to detect a signal to noise ratio or a signal strength of the signal from the upper level device to generate a signal to noise ratio value or a signal strength value of the signal from the upper level device.

9. The control device according to claim 8, wherein the selecting a relay device comprises:

a signal comparison device, configured to compare a signal to noise ratio value or a signal strength value of the signal from the upper level device with a predetermined threshold to generate a comparison result;

a first selecting means, configured to perform the following operations according to the comparison result:

- if the signal to noise ratio value or signal strength value is greater than the predetermined threshold, selecting a decoding forward relay mode of operation to relay the signal from the upper level device;

- if the signal to noise ratio value or signal strength value is less than the predetermined alarm value, for selecting the amplification forward relay operation mode to relay the signal from the upper level device.

The control device according to claim 7, wherein the signal quality related information includes a code check result, and the signal detecting device further includes:

a decoding device, configured to decode the signal from the upper-level device to generate a decoded signal;

a code check device, configured to perform code check on the decoded signal to generate a code check The result.

The control device according to claim 10, wherein the selecting the relay device further comprises:

a second selecting means, configured to perform the following operations according to the code check result:

- if the code check result is correct, then selecting a decoding forward relay mode of operation to relay the signal from the upper level device;

- if the code check result is an error, the first selection means is configured to select an amplification forward (A&F) relay mode of operation to relay the signal from the upper level device.

The control device according to claim 10 or 11, wherein the code check comprises a cyclic redundancy check or a parity check.