KR101693440B1

KR101693440B1 - Dual Hop Relay Station and the Resource Allocating Method thereof

Info

Publication number: KR101693440B1
Application number: KR1020150140475A
Authority: KR
Inventors: 김태준; 김병관
Original assignee: 충북대학교 산학협력단
Priority date: 2015-10-06
Filing date: 2015-10-06
Publication date: 2017-01-06

Abstract

The present invention discloses a dual hop relay system and a resource allocation method thereof. The dual-hop relay system according to one aspect of the present invention is a dual-hop relay system in which, in a normal mode, an access interval and a relay zone of a downlink are fixedly used, and asymmetric First and second relays for reducing one of the access period and the relay period corresponding to the abnormal channel in the abnormal mode of the channel state; And checking the states of the transmission and reception channels of the first and second relays in each frame and confirming that there is a relay in which one of the first and second relay transmission and reception channels is the abnormal channel, And a base station for instructing to change the operation mode from the normal mode to the abnormal mode.

Description

[0001] The present invention relates to a dual hop relay system and a resource allocation method thereof,

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a resource allocation technique of a relay system, and more particularly, to a dual hop relay system allocating resources in consideration of a channel environment and a resource allocation method thereof.

A typical standard of a relay system is IEEE802.16j, and according to IEEE802.16j, a base station and a relay communicate with each other in a half-duplex decode-and-forward mode. The frame structure of the IEEE 802.16j standard is shown in FIG.

(DL Subframe), the downlink region is an access region (DL Access) for communicating between a base station (BS) and a mobile station (MS) and a relay station Zone and a relay station (DL Relay Zone) communicating between a base station (BS) and a relay (RS).

In the relay standard, the access period is a transmission region for transmitting information received from the BS to the MS, and the relay period can be regarded as a reception region for obtaining information from the BS.

Such relays are used to relay communications to terminals that are far from the base station or have low reception sensitivity.

However, if the environment of one of the transmission channel and the reception channel of the relay deteriorates and smooth communication can not be performed, wireless resources may be wasted in the access period or the relay period of the frame.

For example, if the reception channel of the relay is not good, even if the transmission channel is good, the amount of data received by the relay at the base station is small and the relay may lack data to be transmitted to the terminal.

On the other hand, if the transmission channel between the relay and the terminal is not good while the reception channel between the base station and the relay is good, a lot of data is continuously accumulated in the base station, but the data can not be delivered to the terminal and can be dropped.

Korean Registered Patent No. 10-1445078 (Registration date 2014.09.22)

SUMMARY OF THE INVENTION The present invention has been made in view of the above technical background, and it is an object of the present invention to provide a dual hop relay system and a resource allocation method capable of allocating resources of an access interval and a relay interval in consideration of an asymmetric channel environment do.

The objects of the present invention are not limited to the above-mentioned objects, and other objects not mentioned can be clearly understood by those skilled in the art from the following description.

A dual-hop relay system according to one aspect of the present invention is a dual-hop relay system in which, in a normal mode, an access interval and a relay zone of a downlink are fixedly used, and asymmetric A first relay and a second relay for reducing one radio resource among the access interval and the relay interval corresponding to the abnormal channel in the abnormal state of the channel state; And checking the states of the transmission and reception channels of the first and second relays in each frame and confirming that there is a relay in which one of the first and second relay transmission and reception channels is the abnormal channel, And a base station for instructing to change the operation mode from the normal mode to the abnormal mode.

A method for downlink resource allocation in a dual hop relay system according to another aspect of the present invention is a method for allocating a state of a transmission and reception channel of first and second relays by channel state information from first and second relays, Checking; Confirming whether there is a relay which is an ideal channel in which one channel among the first and second relays is less than a preset reference; And instructing to change the operation mode of the relay, which is the abnormal channel, from the normal mode to the abnormal mode when the relay, which is the abnormal channel, is present, and the normal mode is a mode in which the access channel of the downlink and the relay Wherein the mode is a mode in which a relay zone is fixedly used and an abnormal mode is a mode in which the access interval corresponding to the abnormal channel or the relay interval is shortened.

According to the present invention, the communication performance can be improved by adjusting the amount of radio resources used in the access period and the relay period.

1 shows a frame structure of the IEEE802.16j standard.
FIG. 2 is a configuration diagram illustrating a dual hop relay system according to the present invention; FIG.
3A and 3B are diagrams illustrating a downlink resource allocation structure according to the present invention;
FIG. 4 is a block diagram showing a base station of a dual hop relay system according to the present invention; FIG.
FIG. 5 is a flowchart illustrating a resource allocation method of a dual hop relay system according to the present invention. FIG.

BRIEF DESCRIPTION OF THE DRAWINGS The above and other objects, advantages and features of the present invention and methods of achieving them will be apparent from the following detailed description of embodiments thereof taken in conjunction with the accompanying drawings. The present invention may, however, be embodied in many different forms and should not be construed as being limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the invention to those skilled in the art. Is provided to fully convey the scope of the invention to those skilled in the art, and the invention is only defined by the scope of the claims. It is to be understood that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. In the present specification, the singular form includes plural forms unless otherwise specified in the specification. As used herein, the terms " comprises, " and / or "comprising" refer to the presence or absence of one or more other components, steps, operations, and / Or additions.

Embodiments of the present invention will now be described in detail with reference to the accompanying drawings. FIG. 2 is a configuration diagram illustrating a dual hop relay system according to an embodiment of the present invention, and FIGS. 3A and 3B are views illustrating a downlink resource allocation structure according to an embodiment of the present invention. Referring to FIG.

2, a dual-hop relay system according to an embodiment of the present invention includes a base station BS, first and second relays RS1 and RS2, and a terminal MS.

The base station BS determines the state of a channel (receiving channel of each relay) with each of the first and second relays RS1 and RS2 and the channel between the first and second relays RS1 and RS2 and the MS Of the transmission channel).

The base station (BS) confirms whether there is a relay having asymmetric transmission / reception channel in which a normal channel and an ideal channel coexist.

Herein, the base station BS may request channel state information to the first and second relays RS1 and RS2, and may receive the channel state information on the transmission / reception channel of each relay in response to the channel state information to check the channel state.

Herein, the channel state information includes SNR (Signal To Noise Ratio), SINR (Signal-to-Interference-plus-Noise Ratio) of all preamble signals received by the first and second relays RS1 and RS2 and each MS ) And Carrier to Interference (CINR) information.

For example, the base station BS may classify a channel whose SINR is less than or equal to a preset threshold value as an ideal channel from the channel state information. At this time, the threshold value may be a value that is smaller than a predetermined value (for example, a 1/2 times a value) in the average SINR of each channel as a criterion for determining whether or not normal communication is possible.

In addition, the base station (BS) can determine a channel that failed to receive the channel state information in each predetermined frame period as an ideal channel.

As a result, if there is a relay having an asymmetric transmission / reception channel, the base station (BS) transmits a command to the relay to instruct the relay to change its operation mode from the normal mode to the abnormal mode.

Here, the normal mode may be a mode in which an access interval and a relay interval of a DL frame are fixedly used.

The abnormal mode may be a mode in which the access period or the relay period corresponding to the abnormal channel is minimized and the relay period or the access period corresponding to the normal channel is used at the maximum.

The first and second relays RS1 and RS2 change the operation mode of each transmission / reception channel according to the command of the base station BS and relay the data of the base station BS in each operation mode.

Specifically, in the normal mode, the first and second relays RS1 and RS2 use an access interval and a relay interval for transmission and reception. More specifically, the first and second relays RS1 and RS2 transmit data to the terminal MS in the access zone and receive data from the base station BS in the relay zone. have. As described above, in the present invention, in the normal mode in which there is no channel with a uniform channel environment and no bad state, both the relays RS1 and RS2 use the access interval and the relay interval in a similar manner, RS2) can be treated equally.

On the other hand, the first and second relays RS1 and RS2 minimize the access interval or the relay interval corresponding to the abnormal channel in the abnormal mode and use the relay interval or the access interval corresponding to the normal channel to the maximum.

In detail, the first and second relays RS1 and RS2 are configured to receive a command for requesting a change command and channel state information for an operation mode from a base station (BS) in a downlink frame if the anomalous channel is a transmission channel The rest of the area can be used as a relay section.

The first and second relays RS1 and RS2 may use an access region for a remaining region excluding a partial region for transmitting some data from the DL frame to the terminal if the abnormal channel is a reception channel. Here, some data may be an instruction to notify the terminal MS of the change information (radio resource allocation information) of the access section, and a part of the access section may be the minimum area required to transmit the command to the terminal MS have.

Here, if all the areas of the downlink frame are used as the access period or the relay period, the communication channel can be disconnected because it can not be instructed to operate in a different manner when the environment of the channel is changed. In order to prevent such a problem, according to the present invention, a region other than the minimum region necessary for transmitting an instruction that can be instructed to operate in a different manner at the time of changing the channel environment in the access interval (or relay interval) (Or an access period).

Hereinafter, a specific example of resource allocation in the abnormal mode will be described with reference to FIGS. 2, 3A, and 3B.

When the first and fourth channels in FIG. 2 are ideal channels, the first relay RS1 minimizes the relay interval and can only transmit data to the MS through the third channel, as shown in FIG. 3A. have. At this time, the first relay RS1 may transmit the previously received data and relay the relayed data until the state of the first channel is improved.

The second relay RS2 may minimize the access period and only communicate with the base station BS through the second channel. At this time, the second relay RS2 sequentially stores the data received from the base station BS, and can relay the received data when the fourth channel status is notified from the base station BS.

In Fig. 3A, the relay interval of the first relay RS1 may be used to receive a command of the base station BS. Here, the command of the base station BS may be an operation mode change command, a channel state information request, and the like. In addition, the access interval of the second relay RS2 may be used to transmit some data to the terminal MS.

When the second and third channels of FIG. 2 are an ideal channel, the first relay RS1 removes the access interval and can only perform data reception for the BS through the first channel, as shown in FIG. 3B . At this time, the first relay RS1 sequentially stores the data received from the base station BS, and can sequentially relay the stored data when it is notified from the base station BS that the channel status is improved.

The second relay RS2 can eliminate the relay interval and can only communicate with the MS through the fourth channel. At this time, the second relay RS2 may transmit the previously received data and relay the relayed data, and then have a pause until the state of the second channel is improved.

3B, the access interval of the first relay RS1 may be used to receive some data from the terminal MS. In addition, the relay interval of the second relay RS2 may be used to receive the command of the base station BS.

Meanwhile, the base station BS can not perform data transmission to the first and second relays RS1 and RS2 when both of the channel states with respect to the first and second relays RS1 and RS2 are not good .

As described above, according to the embodiment of the present invention, when the channel state is asymmetric, it is possible to increase the area with a good channel state and to use a channel with poor channel state for data relay, It is possible to prevent radio resources from being wasted unnecessarily when the channel environment deteriorates.

In addition, the embodiment of the present invention can provide a low-cost model in which system complexity is reduced according to various area variables by varying the access period and the relay period of the DL frame in two modes.

Hereinafter, a base station of a dual-hop relay system according to an embodiment of the present invention will be described with reference to FIG. 4 is a block diagram illustrating a base station of a dual hop relay system according to an embodiment of the present invention.

4, a base station (BS) of a dual hop relay system according to an embodiment of the present invention includes a storage unit 410, a control unit 420, and a communication unit 430.

The storage unit 410 stores a threshold value, which is a determination criterion of an ideal channel, channel state information of the first and second relays RS1 and RS2, and an operation mode.

The communication unit 430 receives or transmits data from the first and second relays RS1 and RS2. At this time, it goes without saying that the communication unit 430 is further used to communicate with the MS.

The control unit 420 checks the status of the transmission and reception channels of the first and second relays RS1 and RS2 according to the channel status information from the first and second relays RS1 and RS2 of each frame, And the other channel is a normal channel.

If there is a relay having an asymmetric channel, the control unit 420 may instruct the operation mode of the relay to change from the normal mode to the abnormal mode.

Here, the control unit 420 may include at least one processor. For example, the processor may be a central processing unit (CPU), a graphics processing unit (GPU), a microprocessor, an application specific integrated circuit (ASIC), a field programmable gate array (FPGA)

Thereafter, the control unit 420 can continuously check the channel state information and control the operation mode of the relay to perform downlink resource allocation.

Hereinafter, a resource allocation method of the dual hop relay system according to an embodiment of the present invention will be described with reference to FIG. 5 is a flowchart illustrating a resource allocation method of a dual hop relay system according to an embodiment of the present invention.

Referring to FIG. 5, the BS requests channel state information to the first and second relays RS1 and RS2 of each frame (S510). At this time, the first and second relays RS1 and RS2 request channel state information to each frame terminal MS and transmit the channel state information including its own channel state and the channel state information of the previously received MS Information can be transmitted to the base station (BS).

In step S520, the BS determines whether there is a relay channel having an asymmetric transmission / reception channel between the first and second relays RS1 and RS2 using channel state information. Specifically, the base station BS determines whether there is an abnormal channel in one of the transmission channel and the reception channel of the first relay RS1 and the abnormal channel exists in one of the transmission channel and the reception channel of the second relay RS2 If the

At this time, the base station BS can determine that the channel is an abnormal channel if the SNR is less than a preset threshold value from the channel state information.

If there is a relay whose asymmetric channel state exists, the base station BS instructs the corresponding relay to change the operation mode to the abnormal mode (S530). At this time, the relay receiving the instruction can change the operation mode to the abnormal mode, reduce the access interval or relay interval corresponding to the abnormal channel, and increase the other area to communicate.

As described above, the embodiment of the present invention can overcome the performance degradation caused by the asymmetry of the channel environment when the channel state is asymmetrical, and it is possible to prevent unnecessary radio resources from being wasted when the channel environment deteriorates.

While the present invention has been described in detail with reference to the accompanying drawings, it is to be understood that the invention is not limited to the above-described embodiments. Those skilled in the art will appreciate that various modifications, Of course, this is possible. Accordingly, the scope of protection of the present invention should not be limited to the above-described embodiments, but should be determined by the description of the following claims.

BS: base station MS: terminal
RS1: first relay RS2: second relay

Claims

In the normal mode, an access interval and a relay zone of a downlink are fixedly used. In an abnormal mode of an asymmetric channel state in which a normal channel and an ideal channel exist in the transmission / reception channel, First and second relays for reducing one of radio resources of an access period and a relay period; And
Each of the first and second relays being connected to the first relay and the second relay, wherein the first relay and the second relay are connected to each other, And a base station for instructing to change the mode from the normal mode to the abnormal mode,
Wherein the first and second relays are configured to receive a command for requesting a change command and channel state information for the operation mode from the base station in the downlink frame if the abnormal channel is a transmission channel, Storing data received from the base station through the access interval in the abnormal mode and sequentially transmitting the stored data to the terminal when the base station is switched to the normal mode according to an instruction from the base station In double hop relay system.

2. The base station according to claim 1,
Reception channel of the first and second relays based on channel state information including information on a state of the transmission / reception channel received from the first and second relays of the first and second relays, .

3. The apparatus of claim 2, wherein the first and second relays comprise:
Wherein the second hop relay system queries the each frame terminal and receives the response from the terminal to check the status of its own transmission channel.

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2. The apparatus of claim 1, wherein the first and second relays comprise:
Wherein if the anomalous channel is a reception channel, the access section uses the remaining region excluding the partial region for transmitting the resource change information to the terminal in the downlink frame.

7. The apparatus of claim 6, wherein the first and second relays comprise:
Wherein in the abnormal mode, after relaying the data received from the base station to the relay section, the relay device has a pause until switching to the normal mode according to the instruction of the base station.

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