JP2008511210A - Transmission relay method and apparatus - Google Patents

Abstract

The present invention provides a method that enables transparent relay of data to improve the performance of a mobile phone system. In particular, relaying on the uplink is performed by a fixed entity called a transparent relay (TR). The base station may assign one or more TRs to relay data transmissions associated with a particular CID (eg, a particular subscriber station) on the uplink.

Description

  The present invention relates generally to information relaying, and more particularly to a method and apparatus for relaying information within a communication system.

  Wireless communication systems are well known in the art. In many such systems, remote communication units (at least some may be mobile) communicate with each other and / or others via system infrastructure (eg, fixed position transmitters and receivers). To do. In general, a wireless communication system is characterized by a corresponding communication range (usually characterized by one or both of a transmission range and a reception range), and beyond that communication range, the wireless communication capability of the system infrastructure is It cannot spread effectively.

  Repeaters are also known in the art. Such devices typically serve to increase the communication range of a given communication system (by increasing the transmission and / or reception range). This mechanism allows, for example, a relatively low power remote communication unit to effectively communicate with a relatively distant system receiver even though it is outside the effective range of the distant system receiver. . Such repeaters often operate in an autonomous and automatic mode and repeat any transmission that has been successfully received.

  Despite various improvements being made to both the system and the remote communication unit, unfortunately, even if there is a communication unit within the communication range of a given communication system, its transmission is at a predetermined desired level. There still exists time and circumstances that are not reliably received with quality of service. There are various causes for such a result. For example, but not limited to, shadow fading and other propagation problems. Performance requirements can also have an impact. For example, if the demand for data transfer rate (which often leads to a corresponding increase in bandwidth) continues to increase, the remote communication unit (otherwise within range) will send the desired level of service It usually happens that the ability to perform normally without a significant increase in power is impaired. Accordingly, there is a need for a method and apparatus for relaying information within a communication system that addresses the aforementioned problems.

  The present invention provides a method that enables a transparent relay of data to improve the performance of a mobile phone system. In one embodiment, one or more relays are deployed in the sector of the cell. These relays are called transmissive relays (TR). This is because the present invention operates those relays in the system in a manner that is almost “transparent” from the perspective of the subscriber station in the cell. In one example, as shown in FIG. 1, three TRs are deployed in a sector at a location selected to provide significant link budget improvements to a subscriber station (SS) located far from the base station (BS). Can be done.

  In one embodiment of the present invention, multiple TRs (eg, one or more but may be a subset of the total number of TRs in a sector) are relayed to specific TRs in these TRs A command may be issued to (or act). In this case, the selected TR monitors (receives and demodulates / decodes) uplink data transmission performed by the SS. The selected TR then re-encodes and re-transmits the data on a different channel resource (eg, different time slot, different sub-channel, different spreading code, etc.) than the SS used for the original transmission. To do. Transmissions from each selected TR can be made on the same channel resources to obtain macro diversity benefits (in this case, the TR preferably arrives almost synchronously with the BS from the selected TR) Synchronized to the BS timing and frequency).

  A method is also provided for deleting a transmission from any selected TR whenever the selected TR fails to correctly receive / decode a data transmission from the SS. This method includes leaving the channel resources allocated to the TR for transmission empty. By using this method, all TRs in a sector can be made into a single group, and a group ID (for example, a multicast group ID) can be assigned. Then, SS monitoring and TR resource allocation to a group can be performed much more efficiently than when separate commands or allocations are sent to each TR. If all TRs in a sector are activated for a particular SS transmission, some TRs will correctly decode the SS transmission (eg close to SS) and others (eg from SS) It is expected that there will be some distant). Even in such a case, effective macro diversity can be realized. This is because TRs that correctly decode SS transmissions transmit together, but TRs that did not successfully decode SS transmissions remain silent on the channel resources allocated to the TR group for transmission of SS data. It is. A major advantage of this embodiment is that it is not necessary to “hand off” from one TR to another as the SS moves across the cell. On the contrary, the present invention provides an effective method for automatically utilizing the best TR within a sector.

  In a further embodiment, one or more TRs are instructed to monitor data transmissions from multiple SSs. For example, the selected TRs can be given a list of connection IDs (CIDs), which allows the selected TRs to transmit uplink data on all uplink channel resources assigned to these CIDs. It means that it is instructed to monitor. Further, an allocation used by the TR for transmitting data received from the SS (for example, retransmitting data from the SS) is given to the selected TR as an uplink channel resource allocation. As an efficient allocation method, it is possible to give the TR a block resource allocation, and the TR uses a predetermined data ordering rule to transmit all TRs from the same data portion (eg from different SSs). A method of ensuring that transmissions from multiple TRs do not interfere with each other, but achieve a combination of macro diversity at the BS, ensuring that (data segments) are sent on exactly the same corresponding resource Provided. As a further aspect of the present invention, the data transfer rate from different SSs can be different, and the data transfer rate used by TR can be different from SS. In this case, the BS considers the modulation and coding rate used by the SS in the relay and the modulation and coding rate used by the TR in calculating the overall required channel resource allocation required for the TR. (See later examples in the literature). In this case, each selected TR preferably uses the same modulation and coding rate to maintain macro diversity benefits.

In a further embodiment, a method is provided for selecting and adjusting the modulation and coding rate used for transmission.
In a further embodiment, the BS stores the received signal from the SS received on one set of channel resources and combines the stored signal with the received signal from the TR on a different set of channel resources. As a result, a further form of macro diversity is realized. This is because the signals from SS and TR are combined in the BS as a signal processing step.

  By combining the above-described embodiments, the maximum overall function can be realized. Not only the various aspects of these embodiments, but also aspects of further embodiments are described below.

  The detailed embodiments shown below are described in the context of an ongoing IEEE 802.16e standardization effort. Although a detailed solution for the 802.16e OFDMA mode is presented, the present invention is applicable to other systems. The initial letters used in this document are listed in Table 1.

ＵＬ＿ＭＡＰは、アップリンク上での資源割り当てを特定するメッセージである。このメッセージは、資源割り当て以外の情報（例えば適応アンテナ処理またはアップリンクリレーについての情報）を伝えるように拡張することができる。

UL_MAP is a message specifying resource allocation on the uplink. This message can be extended to convey information other than resource allocation (eg, information about adaptive antenna processing or uplink relay).

  The REG-REQ message is a “registration request” message. This is a message sent by the SS after initial ranging. This message is a prerequisite before any data transmission and is acknowledged by the BS by sending a REG-RSP or “registration response” message.

  The relay technology described above can be applied to the uplink for IEEE 802.16e OFDMA. Even when the cell radius is reasonable (2 km), there is a significant link budget problem on the uplink that drastically reduces the uplink data rate and system throughput. The solution presented here allows a simple one-hop relay to be seamlessly introduced on the uplink to address this problem. Since downlink transmissions do not relay at all, the complexity of the relay is greatly reduced.

The solution presented here has the following advantages.
A transparent relay (T-relay) is a simplified unit that requires only a small number of layer 1 operations and execution of a minimum set of layer 2 tasks. Also, it is not necessary to connect the relay to the network.
O The relay process is a transparent process with very few signal changes and no SS changes necessary to accommodate the relay enablement process.
O One or more T-relays can be implemented in each sector. A particular T-relay need not be aware of other T-relays.
○ Since the BS is always in a state of controlling transmission, the reliability of transmission increases.
O The architecture still allows hybrid ARQ (HARQ) to run on the uplink.

  The difference in PA power between SS and BS suggests that the solution can be adapted to provide the necessary support for the uplink (but not included in the downlink). As a result, cost-effective realization creates a dependency between the relay and the BS, ensuring a low cost of the relay while ensuring a robust and reliable transmission overseen by the central authority. Can do. Cost efficiency is achieved by reducing relay complexity so that the relay focuses only on layer-one operations and a minimum set of layer-two tasks. Also good. In addition, the control message need not be relayed, only the bearer data needs to be relayed. Also, the system layout is simplified by the transmission relay (T-relay) configuration. If these T-relays are deployed in an existing cell, the uplink design is effective without the need to re-work cell design (which may be necessary when adding microcells to achieve the same purpose) A range issue can be addressed.

  FIG. 2 shows possible communication paths between the BS, SS and T-relay. Shown in FIG. 2a is a typical communication path in a mobile phone system where the T-relay is disabled. The BS adjusts resources in the cell by distributing control information and arbitrating access requests. In addition, the BS transmits bearer data directly to the SS and receives bearer data directly from the SS. FIG. 2b shows the communication path when the T-relay is enabled. Again, the BS adjusts resources in the cell by distributing control information and arbitrating access requests. Furthermore, the BS continues to send bearer data directly to the SS. However, the uplink bearer data from the SS follows a triangular path (first received and detected by the T-relay, then re-encoded and transmitted to the BS by the T-relay). Shown in FIGS. 2c and 2d are two variations on the T-relay configuration. Shown in FIG. 2c are a plurality of active s-relays that simultaneously carry SS bearer data to the BS. FIG. 2d shows a situation where relay and non-relay uplink communications coexist simultaneously. A major and very beneficial aspect of the T-relay configuration is that the SS may not be fully aware of the presence of relays in the system. Other control related uplink functions (eg ranging and bandwidth requirements) are still handled by the direct SS-BS path to simplify the relay scheme.

  In the broadest sense, the above procedure is the minimum necessary to increase the uplink bearer data transmission rate. If the T-relay cannot be used, the data rate cannot take into account the relay. If a T-relay can be used, the data rate can be much higher considering the T-relay. Since each data transmission can adapt to the channel condition, the condition is that even if a T-relay can be used, the T-relay may not be used if the quality of the direct link to the BS is sufficient. It can be something. Usually, the determination as to whether or not to use the T-relay is made for each transmission, but may be performed on a longer-term average channel quality basis (for example, shadowing is considered but fast fading is not considered). A T-relay (more generally, one or more T-relays) is a subordinate relay. This is because the BS assigns resources to the SS-T-relay link.

<Action to be performed>
As described above, the relay process is completely transparent to the SS, so no further action is required. However, it is necessary to set up and maintain a link between the T-relay and the BS. In the following, the implementation of various tasks that need to be performed will be described in detail.

<Network entry and initialization>
The network entry and initialization process is the same as in a conventional SS, except that at some point (registration process) the unit must identify itself as a T-relay.

<Relay assignment to connection (listening)>
The relay assignment process is performed on a frame-by-frame basis. A CID is assigned to each T-relay (or group of T-relays). The transmission of this assigned CID needs to be monitored in the uplink part of the current frame by each T-relay. Thus, by decoding the UL_MAP, each T-relay knows all the resources that need to listen and attempt detection. Note that a T-relay may monitor one or more connections (eg, one or more SSs) or may be part of one or more multicast groups. For example, a T-relay may be assigned to monitor two different connections, and the T-relay may be assigned various CIDs (eg, a special CID if the T-relay is activated, or It may even be a multicast CID if the T-relay is part of a group of activated relays).

  Alternatively, instead of doing on a frame-by-frame basis, the assignment can remain valid until a future assignment or deallocation is received. Alternatively, the assignment can be valid only for a predetermined time (for example, 10 frames).

<Communication for relay assignment (transmission)>
Resource allocation for transmission from the T-relay to the BS is also performed on a frame-by-frame basis. Allocation of resources to each T-relay (or group of T-relays) is done via an existing UL_MAP_IE message. Each T-relay only relays connections where it has successfully decoded the data.

<Modulation / coding method selection>
Since the T-relay relays back only the connections for which it has successfully decoded the data, the BS can start by first assigning a high MCS to the SS. The T-relay monitors the link. If the T-relay cannot successfully decode the data, it will not send anything to the BS. If the BS does not receive anything, it knows that the selected MCS is too high and then assigns the lower MCS to the SS. This is done until the BS receives something from one or more T-relays. This process allows for initial MCS selection. After this initial MCS selection, the HARQ process can fine tune the MCS selection.

  Alternatively, the BS can perform blind AMC selection based on some open loop approximation. The simplest method of MCS selection would be to use aggressive default values in the hope that the SS is close to either one of the relays or the BS. The system may mitigate all selected insufficient AMC levels based on hybrid ARQ and retransmission.

  Alternatively, the relay may report on the basis of information after eavesdropping the ranging channel. The relay can report this information using the ranging channel. Alternatively, a dedicated resource (eg, one RE) can be reserved by the BS for this process. To avoid collisions between all relays, each relay is assigned a Walsh code and distributes the assigned coded report.

  If there is only one relay, the relay can tie the MCS information together with the data to relay. This solution is not applicable when multiple relays and RF are combined. The relay can send a request to increase MCS on the ranging channel. Alternatively, the CDMA embodiment described above can be applied. Also, some type of analog feedback may be used to inform the base that it can support a higher MCS (eg, by changing the transmit power).

The relay can also send a beacon at a predetermined time, and the SS can measure the received power and make its own MCS request.
<Hybrid ARO process>
This architecture can adapt HARQ to the uplink. The T-relay (or group of T-relays) stores the data received from the SS in a buffer. If the T-relay successfully decodes the packet, the T-relay sends data to the BS on resources explicitly allocated on the uplink. If the decoding is not successful, the T-relay (or group of T-relays) sends nothing. If nothing is received, the BS knows that the transmission was not successful and sends control for the next HARQ transmission.

<Text changes to be made to the IEEE 802.16 standard>
[Add the following paragraph after the third paragraph in Chapter 6.1]
In order to improve the uplink data rate, a transparent relay on the uplink may be enabled. To achieve a higher data rate and / or capacity on the uplink by placing a transparent relay (TR) in the cell and decomposing the SS-BS link into an SS-TR link and a TR-BS link On an “when useful” basis or when the quality of the SS-BS link is unacceptable. This process is completely transparent to SS. The SS does not recognize that it is being relayed.

[In the 6.3.3.2.7 Registration Request (REG-REQ) message, the following bold text is inserted immediately before 6.3.3.2.3.8]
The REG-REQ may include the following TLVs:
(...)
Transparent relay capability (11.7.19)
[In the 6.3.3.2.8 Registration Response (REG-RSP) message, the following bold text is inserted immediately before 6.3.3.2.3.9]
The REG-RSP may include the following TLVs:
(...)
Transparent relay capability (11.7.19)
[Add new 6.3.3.2.3.47.8.8]
6.3.3.2.3.43.7.7.8 Compact_UL_MAP transparent relay monitor. The transparent relay monitor information element provides as SSCID a list of SSCIDs whose transmission should be monitored (detected) during the UL portion of the current frame and relayed in the next frame.

[新たな６．３．２．３．５７章を追加する］
６．３．２．３．５７ 透過リレーＣＩＤ割り当て（ＴＲ−ＣＩＤ）メッセージ
基地は、１つ以上の二次のリレーのＣＩＤを透過リレーに割り当てることを、リレーモニタ命令を送りまたモニタしたＳＳデータの再送信用の資源を割り当てるために行なう。リレーＣＩＤは、ただ１つの透過リレーに割り当てても良いし、複数の透過リレーに割り当てても良い。受信したら、ＳＳは、前に割り当てたリレーＣＩＤをすべて削除して、新たに割り当てるものを採用する。

[Add new chapter 6.3.2.3.57]
6.3.2.3.57 Transparent Relay CID Assignment (TR-CID) The message base sends and monitors the SS data to send and monitor a relay relay to assign one or more secondary relay CIDs to the transparent relay. To allocate resources for re-transmission credit. The relay CID may be assigned to only one transparent relay, or may be assigned to a plurality of transparent relays. Upon receipt, the SS deletes all previously assigned relay CIDs and adopts newly assigned ones.

パラメータは以下のとおりである。

The parameters are as follows:

CID (in general-purpose MAC header)
SS primary management CID.
Transaction ID
A unique identifier for this transaction assigned by the caller.
All other parameters are coded as TLV tuples.
Relay CID (see 11.16).
(6.3.3.2.58) Transparent Relay CID Assignment ACK (TR-CK) Message This message is sent in response to the TR-CID Assignment message.

パラメータは以下のとおりである。

The parameters are as follows:

CID (in general-purpose MAC header)
SS primary management CID
Transaction ID
A unique identifier for this transaction assigned by the caller. A zero verification code means that the request was successful. Non-zero means failure.

[Add new chapter 11.7.19]
11.7.19 Transparent Relay Capability This field indicates whether the unit is a normal SS or a transparent relay.

［新たな６．３．１８章を追加する］
６．３．１８章 透過リレー動作
アップリンク上でのデータレートを向上させるために、ある程度のアップリンク送信をリレーすることが優位である場合がある。アップリンク上でのリレーは、透過リレー（ＴＲ）と言われる固定されたエンティティによって行なう。ＢＳは、１つ以上のＴＲを、アップリンク上で特定のＣＩＤ（例えば特定のＳＳ）に関連するデータ送信をリレーすることに割り当てても良い。図３にプロセスを示す。ＵＬ＿ＭＡＰにおいて、アップリンク資源割り当てを送信ＳＳに送り、またＵＬ＿ＴＲ＿モニタ＿ＩＥを含めることで、ＴＲまたはＴＲのグループに、１つ以上のＳＳＣＩＤに関連するアップリンク送信をモニタするように命令を出す。アップリンクにおいて、ＳＳは送信し、またＴＲは、モニタすることにＴＲが割り当てられた送信をモニタする。モニタした送信を、ＴＲが復調およびデコードして、その送信を次のフレームにおいて再エンコードおよび再送信（リレー）できるようにする。次のフレームでは、第２のＵＬ＿ＭＡＰメッセージにおいて、作動状態の各ＴＲが、リレー送信に対する各ＴＲの資源割り当てを受信する。この資源割り当ては、ＴＲＣＩＤごとにまたはマルチキャストグループＴＲＣＩＤに対して、行なう。割り当てをマルチキャストグループＴＲＣＩＤごとに行なう場合、これらのＴ−リレーは、モニタした送信を同時にリレーして、マクロダイバーシティゲインをもたらすものと予想される。

[Add new 6.3.18]
6.3.18 Transparent relay operation To improve the data rate on the uplink, it may be advantageous to relay some uplink transmission. Relaying on the uplink is performed by a fixed entity called a transparent relay (TR). The BS may assign one or more TRs to relay data transmissions associated with a particular CID (eg, a particular SS) on the uplink. The process is shown in FIG. In UL_MAP, the uplink resource allocation is sent to the sending SS and the UL_TR_monitor_IE is included to instruct the TR or group of TRs to monitor uplink transmissions associated with one or more SSCIDs. On the uplink, the SS transmits and the TR monitors the transmissions that the TR is assigned to monitor. The monitored transmission is demodulated and decoded by the TR so that it can be re-encoded and re-transmitted (relayed) in the next frame. In the next frame, in the second UL_MAP message, each active TR receives each TR's resource allocation for relay transmission. This resource allocation is performed for each TRCID or for the multicast group TRCID. If assignment is made per multicast group TRCID, these T-relays are expected to relay the monitored transmissions simultaneously, resulting in macro diversity gain.

  The MAC PDU is transmitted in exactly the same relative order upon reception and is modulated and coded using the specified modulation coding scheme (MCS, based on UIUC) in the UL_MAP_IE destined for the TR. Encoding the MAC PDU of each individual SS separately is performed as if the BS sent a separate assignment for each SS in the relay. If the TR did not correctly decode the data from a particular user (CID), the TR does not relay that data and leaves this part of the assignment empty.

  FIG. 4 shows an example of TR resource allocation. In the example described, the TR must relay three transmissions. MAC, PDU, S1, MAC, PDU, S2, and MAC, PDU, S3. These transmission assignments appeared in this same relative order in the previous frame. The TR receives its resource allocation (in UL_MAP_IE) to relay three transmissions with 64-QAM · R = 1/2 and the amount of subchannels necessary to perform the relay operation. The first PDU to be relayed (MAC PDU S1) is modulated and encoded using the new MCS and mapped onto the first resource. Since TR did not receive MAC / PDU / S2 correctly, TR does not transmit anything to S2, but leaves the portion of the allocated resource that should have relayed this PDU empty. Resources for relaying MAC, PDU, and S3 are allocated after resources provided to MAC, PDU, and S2. This TR resource allocation process allows the BS to know where to find the data relayed for each MAC / PDU, even though the relay uses an MCS different from the SS. Macro diversity is also realized when multiple TRs are assigned to relay the same CID.

[Add new 8.4.5.4.15]
8.4.5.5.4.15 UL_MAP Transparent Relay Monitor The SSCID should be monitored (detected) during the UL portion of the current frame and relayed in the next frame as an SSCID by the transparent relay monitor information element. A list of

［新たな１１．１７章を追加する］
１１．１６章 透過リレーＣＩＤ割り当て
このフィールドの値によって、ＢＳによって特定の透過リレーに割り当てられるＣＩＤが特定する。このフィールドは、ＴＲ−ＣＩＤ割り当てメッセージ内に存在するとする。ＢＳは、ＵＬ＿ＭＡＰ透過リレーモニタＩＥとコンパクトＵＬ＿ＭＡＰ＿透過リレーモニタＩＥとにおける割り当てられた値を用いて、リレーに、特定のアップリンク割り当てをモニタするように命令を出すものとする。ＢＳは、ＵＬ＿ＭＡＰＩＥでの割り当てられた値を用いて、モニタしたＳＳデータを再送信するための資源を割り当てるものとする。

[Add new chapter 11.17]
11.16 Transparent Relay CID Assignment The value of this field specifies the CID assigned by the BS to a specific transparent relay. This field is assumed to be present in the TR-CID assignment message. The BS shall instruct the relay to monitor specific uplink assignments using the assigned values in the UL_MAP transparent relay monitor IE and the compact UL_MAP_transparent relay monitor IE. The BS shall allocate resources for retransmitting the monitored SS data using the value allocated in UL_MAPIE.

特に特定の実施形態を参照して図示して本発明を説明したが、当業者であれば理解するように、本発明の趣旨および範囲から逸脱することなく、形態および詳細の種々の変形を本発明において行なっても良い。このような変形も添付の請求項の範囲に入ることが意図されている。

Although the invention has been described with particular reference to specific embodiments, it will be understood by those skilled in the art that various changes in form and detail may be made without departing from the spirit and scope of the invention. You may carry out in invention. Such modifications are also intended to fall within the scope of the appended claims.

The block diagram of a base station and a subscriber station. Fig. 4 illustrates possible communication paths between a base station, a subscriber station and a relay. FIG. 5 is a call flow diagram illustrating assignment of one or more relays. Indicates resource allocation to the relay.

Claims (7)

A relay device is a method for relaying information in a communication system,
Receiving a message representative of a subscriber station to be monitored;
Receiving an assignment message representing a relay-base resource;
Receiving a transmission from a subscriber station;
Demodulating and decoding subscriber station transmissions;
Remodulating and re-encoding the subscriber station transmission;
Relaying the re-modulated and re-encoded transmission via a relay-base resource, wherein the relaying is relayed in a predetermined order.   The method of claim 1, wherein relaying transmissions in a predetermined order comprises relaying transmissions in the order in which the transmissions are received.   The method of claim 1, wherein relaying transmissions in a predetermined order comprises relaying transmissions in the same relative order as assignments in previous frames.   Relaying the transmission comprises relaying only the correctly demodulated and decoded transmission by leaving the portion of the assigned relay-base resource associated with the transmission that was not decoded correctly empty. Item 2. The method according to Item 1.   Relaying the re-modulated and re-encoded transmission via the relay-base resource relays the re-modulated and re-encoded transmission via the relay-base resource that another relay device uses substantially simultaneously. The method of claim 1 comprising:   The method of claim 1, further comprising determining a modulation and coding rate to utilize when remodulating and re-encoding one or more subscriber station transmissions.   The method of claim 1, further comprising the step of sending a message representative of relay capability before relaying transmissions from one or more subscriber stations.

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