WO2011079550A1

WO2011079550A1 - Method for orthogonal transmission of uplink and downlink information in frequency devision duplex relay system

Info

Publication number: WO2011079550A1
Application number: PCT/CN2010/070958
Authority: WO
Inventors: 周斌; 徐景; 王海峰
Original assignee: 上海无线通信研究中心
Priority date: 2009-12-30
Filing date: 2010-03-10
Publication date: 2011-07-07
Also published as: CN102118764B; CN102118764A

Abstract

Provided in the present invention is a method for orthogonal transmission of uplink and downlink information in a frequency division duplex relay system, which enables relay node of each cell in the system to be in different working states, namely, in a same time period, the relay node of a cell is in a state of receiving information, i.e. the relay node of the cell receives information sent from a base station of the cell on a first subband of a downlink frequency band and signals sent from each remote user equipment of the cell on a first subband of an uplink frequency band; while the relay node of a neighbouring cell of the said cell is in a state of transmitting information, i.e. the relay node of the neighbouring cell transmits information to a base station of the neighbouring cell on a second subband of the uplink frequency band and to each remote user equipment of the neighbouring cell on a second subband of the downlink frequency band. In this way, interference between neighbouring cells can be avoided effectively.

Description

Uplink and downlink information orthogonal transmission method in frequency division duplex relay system

The present invention relates to a method for orthogonal transmission of uplink and downlink information in a communication system, and more particularly to a method for orthogonal transmission of uplink and downlink information in a frequency division duplex relay system. Background technique

In recent years, relay-enhanced cellular wireless communication technology has become a rapidly developing research field, and this technology is likely to become a core technology for ensuring efficient use of spectrum in future communication systems. By adding a fixed relay node (FRN) to an existing cellular system to form a relay enhanced celet (REC), REC can obtain many benefits: such as expanding cell coverage and improving Cell border user service quality, fast and flexible temporary network deployment, etc.

As shown in FIG. 1 , in a relay enhanced cellular system, a base station (BS) is deployed at a central location of a REC, and a plurality of fixed relay nodes (FRNs) are deployed at a cell edge. The purpose of deploying a fixed relay node is to Increase throughput or coverage extension. In a relay-enhanced cellular system, all user equipments (UEs) are classified into two types: a two-hop user terminal (remote UE, RUE) and a one-hop user terminal (local UE, LUE), where, LUE Can communicate directly with the BS. There is no direct connection between RUE and BS, and it is necessary to communicate with the BS through the relay of the fixed relay node. At the same time, all radio links in the REC are also classified into three categories: BS-FRN link, FRN-RUE link and BS-LUE link. How to effectively allocate all the radio resources of REC to the above three types of links is a research hotspot in recent years. The various proposed solutions include various techniques such as orthogonal resource usage, partial reuse, and full reuse.

It is well known that Orthogonal Frequency Division Multiplexing (OFDM) systems are more difficult to operate and manage at the cell edge than code division multiple access (CDMA) systems. At the cell edge, the CDMA system uses the scrambling code to protect the UE from excessive inter-cell interference; however, OFDM systems cannot use this technique. Therefore, for OFDM systems, in 3GPP LTE systems, the following three techniques are often discussed to solve inter-cell interference problems:

1) Small interval interference randomization

2) Small interference cancellation

3) Small interval coordination / avoidance

However, the fixed relay node is not included in the cell of the LTE system, and therefore the above three methods cannot effectively solve the inter-cell interference problem of the fixed relay node enhanced cellular system.

In the fixed relay node enhanced cell, because it adds a new network node in the existing cellular layout. Fixed relay nodes make the inter-cell interference environment more complicated, that is, in addition to inter-cell interference, interference also exists in BS and LUE, BS and RUE, BS and FRN, FRN and LUE, FRN and RUE and many other network nodes. Among the various types of inter-cell interference described above, FRN and RUE are interferences that require special attention. Since the FRN is usually deployed at the cell edge to expand the cell coverage, the distance from the FRN to the neighboring cell will be closer than the BS to the neighboring cell, as shown by the arrow in Figure 2, that is, in the adjacent two In the edge area of the cell, the signal sent by the FRN of the right cell may seriously interfere with the RUE of the left cell. In the cellular system shown in FIG. 3, when the FRN1 of the cell where the BS2 is located sends information to the UE at the cell edge, BS1 The FRN2 and FRN3 of the cell in the cell may cause interference to the UE, so measures must be taken to prevent the RUE in the REC from undergoing severe inter-cell interference from the neighboring cell FRN.

As shown in Fig. 4, it is an existing half-duplex frequency division duplex relay scheme, which is adopted by the WINNER I I project in Europe. In the REC, downlink transmission includes three types: transmission from BS to FRN (BS -> FRN), transmission from BS to LUE (BS -> LUE), transmission from FRN to RUE (FRN -> RUE); The uplink transmission also includes three types: transmission from FRN to BS (FRN -> BS), transmission from LUE to BS (LUE -> BS), transmission from RUE to FRN (RUE -> FRN). The uplink and downlink transmissions occupy symmetric frequency bands in a frequency division duplex mode, as shown in FIG. The frequency bands used for uplink and downlink transmissions need to be further subdivided so that different types of uplink/downlink transmissions are used orthogonally, for example: BS -> FRN downlink transmission and BS -> LUE downlink transmission.

The reference scheme is: In phase 1 (one phase may include one or more consecutive subframes), BS1 of cell A transmits signals simultaneously to FRN1 and LUE1 using orthogonal resources on the downlink frequency band, where: BS1->FRN1 downlink The frequency band used for transmission is fAl l (Dark Green, BS1->LUE1 The frequency band used for downlink transmission is fA12 (light green, at the same time, BS1 (full duplex) receives fA1 in the uplink frequency band (the signal from LUE1 is received on the purple part, FRN1 (half-duplex) fA22 in the uplink frequency band (receives the signal from RUE1 in red; and correspondingly, the frequency band used for downlink transmission of BS2->FRN2 of neighboring cell B is fAl l, and the frequency band used for downlink transmission of BS2->LUE2 is fA12. At the same time, BS2 (full duplex) receives the signal from LUE2 on the fA21 portion of the uplink frequency band, and FRN2 (half duplex) receives the signal from RUE2 on the fA22 of the uplink frequency band. In phase 2, BS1 is in the upstream frequency band. The signals from LUE1 and FRN1 are simultaneously received on the orthogonal resources, where: FRN1->BS1 uses the frequency band used for uplink transmission as fA22, LUE1_>BS1 uses the frequency band for uplink transmission as fA21, and at the same time, BS1 (full duplex) is in downlink frequency The fA12 part transmits a signal to LUE1, and FRN1 (half duplex) transmits a signal to RUE1 on the fAl l part of the downlink frequency band; correspondingly, the frequency band used for uplink transmission of FRN2->BS2 is fAl l, LUE2-> BS2 for uplink transmission The frequency band is fA21, at the same time, BS2 (full duplex) transmits a signal to LUE1 on the fA12 portion of the downlink frequency band, and FRN2 (half duplex) transmits a signal to RUE2 on the fAl1 portion of the downlink frequency band. As can be seen from FIG. The frequency band occupied by the RUE1-FRN1 link of cell A in uplink/downlink transmission and the B of cell B The frequency band occupied by the RUE2-FRN2 link in the uplink/downlink transmission is the same, so that the interference between the RUE and the FRN of the neighboring cell is very serious (as shown by the dotted line in FIG. 4), therefore, how to mitigate this The serious inter-cell interference phenomenon existing in the relay system has become a technical problem to be solved by those skilled in the art. Summary of the invention

It is an object of the present invention to provide a method for orthogonal transmission of uplink and downlink information in a frequency division duplex relay system to avoid interference in a small interval.

In order to achieve the above and other objects, the uplink and downlink information orthogonal transmission method in the frequency division duplex relay system provided by the present invention is characterized in that: in the same time period, the relay node end of a cell of the communication system is Receiving the information state, that is, the relay node end of the cell receives the information sent by the first subband of the downlink frequency band of the cell base station, and the first subband of the uplink frequency band of each two hop UE of the cell The transmitted signal, and the relay node of the neighboring cell adjacent to the cell is in a state of transmitting information, that is, the second sub-band of the uplink band of the relay node of the neighboring cell sends information to the neighboring cell base station And sending, by the second sub-band of the following line band, information to each two-hop UE of the neighboring cell.

That is, in the first period, the relay node of the first cell only receives the information sent by the first subband of the downlink frequency band of the base station of the first cell and the first of the uplink frequency bands of each two hop UE The information sent by the sub-band, the third sub-band of the downlink of the first cell of the first cell sends information to each hop user in the first cell, and also receives one hop user in the first cell. And transmitting, by the second sub-band of the uplink frequency of the second cell of the second cell adjacent to the first cell, to the base station of the second cell And transmitting, by the second sub-band of the downlink frequency band, information to each two-hop UE of the second cell, where the base station of the second cell is also the third sub-band of the downlink frequency band to each of the second cell The hopping client sends the information, and also receives the information sent by the third subband of the uplink frequency band of each hop user in the second cell; and in the second time period, the relay node of the first cell only Second subband of the above line frequency The base station of the first cell sends information, and the second sub-band of the downlink frequency band sends information to each two-hop user end of the first cell, and the third sub-band of the downlink frequency band of the base station of the first cell Each hop user in the first cell sends information, and also receives information sent by a third subband of each hop user in the first cell; and the relay of the second cell The node receives the information sent by the first subband of the downlink frequency band of the base station of the second cell and the information sent by the first subband of each of the two hops of the uplink frequency band, and the base station of the second cell is similar to the following The third sub-band of the line frequency band sends information to each hop user end in the second cell, and also receives information sent by the third sub-band of each hop user terminal in the second cell.

The first time period and the second time period may alternate with each other; the first time period and the second time period may respectively include one or more consecutive subframes. In addition, the first sub-band of the uplink frequency band may be the same as the second sub-band; the first sub-band of the downlink frequency band may be the same as the second sub-band.

In summary, the uplink and downlink information orthogonal transmission method in the frequency division duplex relay system of the present invention uses the relay node end of one cell in the same period of time, and the relay node end of its neighboring cell is in the transmitting state. The receiving state, thereby effectively avoiding interference between cells. DRAWINGS

FIG. 1 is a schematic diagram of a basic architecture of a conventional relay enhanced cellular system.

2 is a schematic diagram of interference between two adjacent cells in a conventional relay enhanced cellular system.

FIG. 3 is a schematic diagram of interference between two cells of a conventional relay enhanced cellular system.

Figure 4 is a schematic diagram of the information transmission process of the existing half-duplex frequency division duplex relay system.

FIG. 5 is a schematic flowchart of a method for orthogonal transmission of uplink and downlink information in a frequency division duplex relay system according to the present invention.

detailed description

Referring to FIG. 5, the frequency division duplex relay system used in the uplink and downlink information orthogonal transmission method in the frequency division duplex relay system of the present invention includes a first cell and a second cell which are mutually neighbors, where A cell includes a base station BS1, a hop UE LUE1, a relay node FRN1, and a two-hop UE RUE1, the second cell includes a base station BS2, a hop UE LUE2, a relay node FRN2, and a two-hop UE RUE2. . When the information orthogonal transmission is performed in the frequency division duplex relay system, when the relay node of a cell is in the state of receiving information, that is, the relay node of the cell receives the cell base station in the same time period. The information sent by the first sub-band of the following downlink frequency band and the signal sent by the first sub-band of the uplink frequency band of each two-hop UE of the cell, and the relay node end of the neighboring cell adjacent to the cell In the state of transmitting information, that is, the second sub-band of the uplink frequency band of the relay node of the neighboring cell transmits information to the neighboring cell base station and the second sub-band of the following downlink frequency band to each two-hop user of the neighboring cell Send information. The entire process of information transmission will be explained in more detail below.

First, in the first period: the relay node FRN1 of the first cell does not send any information, and only receives the information sent by the first sub-band Π 1 of the downlink band of the base station BS1 of the first cell, and each two hops The information transmitted by the first sub-band f21 of the uplink frequency band of the user terminal RUE1, and the third sub-band 3 of the downlink frequency band of the base station BS1 sends information to each hop UE LUE1 in the first cell, and also receives the information. The information sent by the third sub-band f23 of the uplink frequency band of each hop UE LUE1 in the first cell; and the second sub-band f22 of the uplink frequency of the relay node FRN2 of the second cell to the second cell The base station BS2 transmits information, and the second sub-band 2 of the downlink frequency band is to each two-hop UE of the second cell. The RUE2 sends the information, and the base station BS2 of the second cell sends the information to the one-hop UE LUE2 in the second cell, and also receives one hop in the second cell. The information transmitted by the third sub-band f23 of the uplink band of the UE LUE2. In this embodiment, the first sub-band Π 1 of the downlink frequency band and the second sub-band Π 2 of the downlink frequency band are the same, but cannot be the same as the third sub-band Π3 of the downlink frequency band, and the first sub-band f21 and the uplink of the uplink frequency band The second sub-band f22 of the frequency is the same, but cannot be the same as the third sub-band f23 of the upstream frequency band.

In the next second period: the relay node RUE1 of the first cell transmits only information to the base station BS1 of the first cell and only the second subband of the downlink band, the second sub-band f22 of the uplink frequency Π2, sending information to each of the two hop UEs RUE1 of the first cell, and the third subband Π3 of the downlink of the base station BS1 of the first cell sends information to each hop UE LUE1 in the first cell, At the same time, the information sent by the third sub-band f23 of the uplink frequency band of each hop UE LUE1 in the first cell is received; and the relay node FRN2 of the second cell receives the base station BS2 of the second cell. The information transmitted by the first sub-band Π 1 of the downlink band and the information transmitted by the first sub-band f21 of each of the two-hop UE RUE2, the base station BS2 of the second cell is the same as the third of the downlink band The subband Π3 transmits information to each hop UE LUE2 in the second cell, and also receives information sent by the third subband f23 of each hop UE LUE2 in the second cell.

It should be noted that each time period may include one or more consecutive subframes, and the first time period and the second time period alternately, thereby completing information transmission of the frequency division duplex relay system.

As can be seen from the above, in the first time period, the two-hop UE RUE1 of the first cell sends information to the relay node FRN1 with f21, and the neighboring two-hop UE RUE2 receives the relay node FRN2 for transmission by Π2. The information, obviously, does not cause interference between the two; likewise, in the second period, the two-hop UE RUE1 of the first cell receives the information sent by the relay node FRN1 to Π2, and the adjacent two-hop UE RUE2 sends the information sent by f21 to the relay node FRN2. Obviously, there is no interference between the two.

In summary, the signals of RUE, FRN and LUE in the uplink and downlink information orthogonal transmission method in the frequency division duplex relay system of the present invention are multiplexed together by orthogonal frequency division multiplexing (OFDM). However, since the relay node of one cell is in the state of transmitting information, and the relay node of the neighboring cell is in the state of receiving information, interference between cells can be effectively avoided.

The above-described embodiments are merely illustrative of the principles and effects of the invention and are not intended to limit the invention. Any of the above-described embodiments may be modified by those skilled in the art without departing from the spirit and scope of the invention. Therefore, the scope of the invention should be construed as the scope of the claims.

Claims

O 2011/079550 Claim PCT/CN2010/070958

A method for orthogonal transmission of uplink and downlink information in a frequency division duplex relay system, characterized in that:

During the same time period, when the relay node of a cell of the communication system is in the state of receiving information, that is, the relay node of the cell receives the information sent by the first subband of the downlink band of the cell base station and a signal sent by the first sub-band of the uplink frequency band of each of the two-hop UEs of the cell, and a relay node of the neighboring cell adjacent to the cell is in a state of transmitting information, that is, a relay of the neighboring cell The second sub-band of the uplink frequency band of the node end sends information to the neighboring cell base station and the second sub-band of the downlink frequency band sends information to each two-hop UE of the neighboring cell.

2. The method for orthogonal transmission of uplink and downlink information in a frequency division duplex relay system according to claim 1, comprising the steps of:

1) In the first time period, the relay node end of the first cell only receives the information sent by the first subband of the downlink frequency band of the base station of the first cell and the first subband of the uplink frequency band of each two hop UE The third sub-band of the downlink frequency band of the first cell of the first cell sends information to each hop user in the first cell, and also receives one hop user or more in the first cell. Information transmitted by the third sub-band of the line band; and the second sub-band of the uplink frequency of the relay node of the second cell adjacent to the first cell transmits information to the base station of the second cell, and The second sub-band of the following downlink frequency band sends information to each two-hop user end of the second cell, and the base station of the second cell also sends a third sub-band of the downlink frequency band to each one-hop user in the second cell. Sending information, and simultaneously receiving information sent by a third sub-band of each of the one-hop users in the second cell;

2) The second sub-band of the first cell transmits information to the base station of the first cell, and the second sub-band of the downlink band to the second period The two sub-hops of the first cell send information, and the third sub-band of the downlink of the first cell sends information to each hop user in the first cell, and also receives the first cell. The information transmitted by the third sub-band of the uplink frequency band of each hop user; and the relay node of the second cell receives the information sent by the first sub-band of the downlink frequency band of the base station of the second cell The information transmitted by the first sub-band of the uplink frequency band of each two-hop user terminal, the base station of the second cell also sends information to the one-hop user end of the second cell in the third sub-band of the downlink frequency band, And receiving information sent by a third sub-band of each of the one-hop users in the second cell.

3. The uplink and downlink information orthogonal transmission method in a frequency division duplex relay system according to claim 2, wherein: the first time period and the second time period alternate with each other.

4. The uplink and downlink information orthogonal transmission method in a frequency division duplex relay system according to claim 2, wherein: O 2011/079550 Claims PCT/CN2010/070958 The first time period and the second time period respectively comprise one or more consecutive subframes.

The method for orthogonal transmission of uplink and downlink information in a frequency division duplex relay system according to claim 1 or 2, wherein: the first subband and the second subband of the uplink frequency band are the same.

The method for orthogonal transmission of uplink and downlink information in a frequency division duplex relay system according to claim 1 or 2, wherein: the first sub-band and the second sub-band of the downlink frequency band are the same.