Method and apparatus for transmitting indication in wireless communication system

Abstract

A method and apparatus for transmitting an indication in a wireless communication system is provided. A relay node (RN) transmits an indication which indicates that the RN is either a fixed relay node or a mobile relay node, and receives initial parameters from an operation, administration, and maintenance (OAM) according on the indication. If the RN is the mobile relay node, the initial parameters includes a list of donor eNodeB (DeNB) cells at a trajectory of the RN.

Claims

1. A method for transmitting, by a relay node (RN), an indication in a wireless communication system, the method comprising: transmitting, by the RN, the indication which indicates that the RN is either a fixed relay node or a mobile relay node, to an operation, administration, and maintenance (OAM); and if the indication indicates that the RN is the mobile relay node, and if trajectory of the RN is pre-determined, receiving, by the RN, a list of donor eNodeB (DeNB) cells for the mobile relay node, from the OAM, wherein the DeNB cells for the mobile relay node are cells deployed at the pre-determined trajectory of the RN, if the indication indicates that the RN is the fixed relay node, receiving, by the RN, a list of DeNB cells for the fixed relay node, from the OAM, wherein the DeNB cells for the fixed relay node are cells deployed at a neighbor of the RN, wherein the mobile relay node is deployed on a vehicle which moves along the pre-determined trajectory.

2. The method of claim 1, wherein the mobile relay node is deployed on a train.

3. The method of claim 1, further comprising attaching as a user equipment (UE) for initial configuration before transmitting the indication.

4. A relay node (RN) in a wireless communication system, the RN comprising: a radio frequency (RF) unit for transmitting or receiving a radio signal; and a processor, coupled to the RF unit, that: controls the RF unit to transmit an indication which indicates that the RN is either a fixed relay node or a mobile relay node, to an operation, administration, and maintenance (OAM); and if the indication indicates that the RN is the mobile relay node, and if trajectory of the RN is pre-determined, controls the RF unit to receive a list of donor eNodeB (DeNB) cells for the mobile relay node, from the OAM, wherein the DeNB cells for the mobile relay node are cells deployed at the pre-determined trajectory of the RN, if the indication indicates that the RN is the fixed relay node, controls the RF unit to receive a list of DeNB cells for the fixed relay node, from the OAM, wherein the DeNB cells for the fixed relay node are cells deployed at a neighbor of the RN, wherein the mobile relay node is deployed on a vehicle which moves along the pre-determined trajectory.

5. The RN of claim 4, wherein the mobile relay node is deployed on a train.

6. The RN of claim 4, wherein the processor further attaches as a user equipment (UE) for initial configuration before transmitting the indication.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) FIG. 1 shows network structure of an evolved universal mobile telecommunication system (E-UMTS).

(2) FIG. 2 shows architecture of a typical E-UTRAN and a typical EPC.

(3) FIGS. 3a and 3b show a user-plane protocol and a control-plane protocol stack for the E-UMTS.

(4) FIG. 4 shows an example of structure of a physical channel.

(5) FIG. 5 shows an objective of relay.

(6) FIG. 6 shows an overall E-UTRAN architecture supporting relay nodes.

(7) FIG. 7 shows an example of deployments scenario of a mobile relay node at a high speed train.

(8) FIG. 8 shows a simplified version of an attach procedure for a relay node (RN).

(9) FIG. 9 shows a simplified version of a DeNB-initiated bearer activation/modification procedure.

(10) FIG. 10 shows a simplified version of a startup procedure for an RN.

(11) FIG. 11 shows a simplified version of a detach procedure for a relay node operation in case no UE is connected to a RN.

(12) FIG. 12 shows an example of RN OAM architecture.

(13) FIG. 13 shows an example of a method for transmitting an indication according to an embodiment of the present invention.

(14) FIG. 14 is a block diagram showing wireless communication system to implement an embodiment of the present invention.

DESCRIPTION OF EXEMPLARY EMBODIMENTS

(15) The technology described below can be used in various wireless communication systems such as code division multiple access (CDMA), frequency division multiple access (FDMA), time division multiple access (TDMA), orthogonal frequency division multiple access (OFDMA), single carrier frequency division multiple access (SC-FDMA), etc. The CDMA can be implemented with a radio technology such as universal terrestrial radio access (UTRA) or CDMA-2000. The TDMA can be implemented with a radio technology such as global system for mobile communications (GSM)/general packet ratio service (GPRS)/enhanced data rate for GSM evolution (EDGE). The OFDMA can be implemented with a radio technology such as institute of electrical and electronics engineers (IEEE) 802.11 (Wi-Fi), IEEE 802.16 (WiMAX), IEEE 802-20, evolved UTRA (E-UTRA), etc. IEEE 802.16m is an evolution of IEEE 802.16e, and provides backward compatibility with an IEEE 802.16-based system. The UTRA is a part of a universal mobile telecommunication system (UMTS). 3rd generation partnership project (3GPP) long term evolution (LTE) is a part of an evolved UMTS (E-UMTS) using the E-UTRA. The 3GPP LTE uses the OFDMA in downlink and uses the SC-FDMA in uplink. LTE-advance (LTE-A) is an evolution of the 3GPP LTE.

(16) For clarity, the following description will focus on the LTE-A. However, technical features of the present invention are not limited thereto.

(17) FIG. 8 shows a simplified version of an attach procedure for a relay node (RN).

(18) 1. An RN and a donor eNodeB (eNB) setup a radio resource control (RRC) connection.

(19) 2a. The RN and a mobility management entity (MME) performs non-access stratum (NAS) attach, authentication, security, etc.

(20) 2b. The MME and a home subscriber server (HSS) perform authentication, security, etc.

(21) 3. The DeNB and the MME create a GPRS tunneling protocol control plane (GTP-C) session.

(22) 4a. The RN and the DeNB reconfigure the RRC connection.

(23) 4b. The DeNB and the MME setup an S1 context.

(24) This procedure is similar to a normal user equipment (UE) attach procedure. The DeNB may be aware of which MMEs support RN functionality via an S1 setup response message earlier received from the MMEs. The RN may transmit an RN indication to the DeNB during RRC connection establishment. After receiving the RN indication from the RN, the DeNB may transmit the RN indication and an Internet protocol (IP) address of the S-GW/P-GW function embedded in the DeNB, within an initial UE message, to the MME supporting RN functionality. The MME may select S-GW/P-GW for the RN based on the IP address included in the initial UE message. During the attach procedure, the EPC checks if the RN is authorized for relay operation. Only if the RN is authorized, the EPC accepts the attach procedure and sets up a context with the DeNB. Otherwise the EPC rejects the attach procedure. The RN may be preconfigured with information about which cells (DeNBs) it is allowed to access.

(25) FIG. 9 shows a simplified version of a DeNB-initiated bearer activation/modification procedure.

(26) 1. A DeNB transmits a GTP-C create/update bearer request message to an MME.

(27) 2. The MME transmits an S1-AP bearer setup/modify request message to the DeNB.

(28) 3. An RN and the DeNB reconfigure an RRC connection.

(29) 4. The DeNB transmits an S1-AP bearer setup/modify response message to the MME.

(30) 5a/5b. Direct transfer is performed from the RN to the DeNB, and from the DeNB to the MME.

(31) 6. The MME transmits a GTP-C create/update bearer response message to the DeNB.

(32) This procedure may be used by the DeNB to change the EPS bearer allocation for the RN. This procedure is the same as a normal network-initiated bearer activation/modification procedure.

(33) FIG. 10 shows a simplified version of a startup procedure for an RN.

(34) This procedure is based on a normal UE attach procedure and it consists of the following two phases. This procedure may be defined for a fixed relay node or a mobile relay node.

(35) 1) Phase I: Attach for RN Preconfiguration.

(36) The RN attaches to an E-UTRAN/EPC as a UE at power-up and retrieves initial configuration parameters, including a list of DeNB cells, from an RN operation, administration, and maintenance (OAM). After this operation is completed, the RN detaches from the network as a UE and triggers a phase II. The MME performs the S-GW and P-GW selection for the RN as a normal UE.

(37) 2) Phase II: Attach for RN Operation.

(38) The RN attaches as a relay for setup and operations. The RN connects to a DeNB selected from the list acquired during the phase I to start relay operations. For this purpose, a normal RN attach procedure described in FIG. 8 may be applied. In this case, the RN may provide an RN indicator to the DeNB during an RRC connection establishment. Also, the MME provides an RN support indication to the DeNB at S1 setup. After the DeNB initiates setup of bearer for S1/X2, the RN initiates a setup of S1 and X2 associations with the DeNB. In addition, the DeNB may initiate an RN reconfiguration procedure via RRC signaling for RN-specific parameters.

(39) After the S1 setup, the DeNB performs an S1 eNB configuration update procedure, if configuration data for the DeNB is updated due to the RN attach. After the X2 setup, the DeNB performs an X2 eNB configuration update procedure to update the cell information.

(40) In this phase the RN cells' evolved cell global identifiers (ECGIs) are configured the RN OAM.

(41) FIG. 11 shows a simplified version of a detach procedure for a relay node operation in case no UE is connected to a RN. The detach procedure is the same as a normal UE detach procedure. The DeNB performs the X2 eNB configuration update procedure to update the cell information. The DeNB performs the S1 eNB configuration update procedure, if configuration data for the DeNB is updated due to the RN detach.

(42) The X2 eNB configuration update procedure described above may be used by the DeNB to also transfer application level configuration data of a single neighboring eNB to the RN. Upon reception of an eNB configuration update message, if the served cells contained in the eNB configuration update message belong to the neighbor eNB rather than the DeNB, the RN shall regard the X2 interface between the DeNB and the neighbor eNB as available. The RN will update an X2 availability, the corresponding GU group ID and other information of the neighbor eNB according to the eNB configuration update message.

(43) FIG. 12 shows an example of RN OAM architecture.

(44) Each RN may transmit alarms and traffic counter information to its OAM system, from which it receives commands, configuration data and software downloads (e.g. for equipment software upgrades). This transport connection between each RN and its OAM, using IP, may be provided by the DeNB. RN OAM traffic is transported over the Un interface, and it shares resources with the rest of the traffic, including UEs attached to the DeNB. The secure connection between the RN and its OAM may be direct or hop-by-hop, i.e. involving intermediate hops trusted by the operator for this purpose. The RN OAM architecture described in FIG. 12 refers to normal operating conditions for the RN, i.e. after the initial start-up phase has been completed.

(45) If a network supports both a fixed relay node and a mobile relay node, the startup procedure for the RN, described in FIG. 10, may be applied for the mobile relay node. As the mobile relay node moves, a DeNB which serves the mobile relay node may be changed frequently. For this, according to the conventional art, the mobile relay node needs to perform the UE attach procedure described in FIG. 10 (Phase I) to receive a list of DeNB cells to be changed before the DeNB which serves the mobile relay node is changed. For example, a mobile relay node, put on the top of a high speed train, should perform the UE attach procedure frequently as the change of the DeNB is highly probable, thus, the mobile relay node needs to obtain a list of DeNB cells from an RN OAM frequently.

(46) In addition, in case that the mobile relay node attaches to a new DeNB as the mobile relay node moves, the mobile relay node should perform a detach procedure from a previous DeNB as described in FIG. 11. However, if the mobile relay node performs the detach procedure, an EPS session of the mobile relay node and network/radio resources allocated to a bearer should be released, and therefore, services provided to UEs, attached to the mobile relay node, may be interrupted.

(47) To solve the problem described above, a method for transmitting an indication according to an embodiment of the present invention may be proposed.

(48) FIG. 13 shows an example of a method for transmitting an indication according to an embodiment of the present invention.

(49) In a network supporting both a fixed relay node and a mobile relay node, after completion of attaching as a regular UE for initial configuration, at step S100, an RN transmits an indication which indicates that the RN is either a fixed relay node or a mobile relay node, to an OAM. On receiving the indication from the RN, the OAM may identify a type of the currently attached RN.

(50) At step S110, the OAM transmits initial parameters to the RN. In this case, as the OAM know the type of the attached RN according to the indication received from the RN, the OAM may provide different information respectively according to the type of the RN. If the RN is a fixed relay node, the OAM may provide a list of DeNB cells as conventional arts. If the RN is a mobile relay node, the OAM may provide a list of DeNB cells deployed at trajectory of the relay node because destination and trajectory of the RN is pre-determined when the relay node is deployed at a high-speed train.

(51) According to embodiments of the present invention, when a relay node is a mobile relay node, the relay node does not have to perform a UE attach procedure to receive a list of DeNB cells. The relay node may know a list of DeNB cells at trajectory of the relay node in advance, and the relay node may perform a handover procedure efficiently while moving fast.

(52) FIG. 14 is a block diagram showing wireless communication system to implement an embodiment of the present invention.

(53) A relay node 800 includes a processor 810, a memory 820, and an RF (radio frequency) unit 830. The processor 810 may be configured to implement proposed functions, procedures, and/or methods in this description. Layers of the radio interface protocol may be implemented in the processor 810. The memory 820 is operatively coupled with the processor 810 and stores a variety of information to operate the processor 810. The RF unit 830 is operatively coupled with the processor 810, and transmits and/or receives a radio signal.

(54) An OAM 900 may include a processor 910, a memory 920 and a RF unit 930. The processor 910 may be configured to implement proposed functions, procedures and/or methods described in this description. Layers of the radio interface protocol may be implemented in the processor 910. The memory 920 is operatively coupled with the processor 910 and stores a variety of information to operate the processor 910. The RF unit 930 is operatively coupled with the processor 910, and transmits and/or receives a radio signal.

(55) The processors 810, 910 may include application-specific integrated circuit (ASIC), other chipset, logic circuit and/or data processing device. The memories 820, 920 may include read-only memory (ROM), random access memory (RAM), flash memory, memory card, storage medium and/or other storage device. The RF units 830, 930 may include baseband circuitry to process radio frequency signals. When the embodiments are implemented in software, the techniques described herein can be implemented with modules (e.g., procedures, functions, and so on) that perform the functions described herein. The modules can be stored in memories 820, 920 and executed by processors 810, 910. The memories 820, 920 can be implemented within the processors 810, 910 or external to the processors 810, 910 in which case those can be communicatively coupled to the processors 810, 910 via various means as is known in the art.

(56) In view of the exemplary systems described herein, methodologies that may be implemented in accordance with the disclosed subject matter have been described with reference to several flow diagrams. While for purposed of simplicity, the methodologies are shown and described as a series of steps or blocks, it is to be understood and appreciated that the claimed subject matter is not limited by the order of the steps or blocks, as some steps may occur in different orders or concurrently with other steps from what is depicted and described herein. Moreover, one skilled in the art would understand that the steps illustrated in the flow diagram are not exclusive and other steps may be included or one or more of the steps in the example flow diagram may be deleted without affecting the scope and spirit of the present disclosure.