Selection of Transit Mode During a Random Access Procedure

Abstract

A method for use in a first node in a wireless access communication system. According to the method, the first node controls traffic to and from users, UEs, within a certain area in the system, a cell, and the first node is equipped with a plurality of transmit antennas. The first node can employ a variety of multi antenna transmit modes for downlink transmissions, i.e. transmissions to the UEs, and the first node can carry out a so called Random Access (RA) procedure with UEs which do not have a dedicated uplink resource, i.e. a resource to the eNodeB. According to the method, one and the same downlink multi antenna transmit mode is used by the first node during the RA procedure.

What is claimed is: 
     
         1 . A method for use in a first node in a wireless access communication system, according to which method:
 the first node serves to control traffic to and from user equipments (UEs) in a cell in the system,   the first node is configured to employ a plurality of multi antenna transmit modes for down link transmissions to the UEs on a shared channel, and   the first node is configured to carry out a Random Access (RA) procedure with UEs which do not have a dedicated up link resource for transmission to an eNodeB, the method comprising using one and the same down link multi antenna transmit mode by the first node during the RA procedure on the shared channel.   
     
     
         2 . The method of  claim 1 , wherein the multi antenna transmit mode used by the first node during the RA procedure is configurable by the first node, and wherein the first node reconfigures the used multi antenna transmit mode and signals an indication of the multi antenna transmit mode to UEs in the cell by signaling in a broadcast channel. 
     
     
         3 . The method of  claim 1 , wherein the multi antenna transmit mode used by the first node during the RA procedure is defined by the first node and signaled in a broadcast channel to UEs in the cell. 
     
     
         4 . The method of  claim 1 , wherein the multi antenna transmit mode includes at least one of transmit diversity, spatial multiplexing, and beam forming with dedicated reference signals. 
     
     
         5 . The method of  claim 1 , wherein the first node, after the RA procedure is successfully performed with one of said UEs, continues to use the same multi antenna transmit mode as during the RA procedure with said one UE. 
     
     
         6 . The method of  claim 5 , wherein the method is performed for a UE which performs the RA procedure as part of an initial access procedure or for a UE which is being handed over to the cell and which has not received any information on the RA multi antenna transmit mode during the handover procedure. 
     
     
         7 . The method of  claim 1 , wherein the multi antenna transmit mode used by the first node after the RA procedure is chosen by the first node and is signaled by the first node to the UEs. 
     
     
         8 . A method, performed by a user equipment (UE) in a wireless communication system, the method comprising:
 carrying out a random access (RA) procedure with a first node of the wireless communication system,   wherein said carrying out the RA procedure comprises receiving at least a random access response message transmitted by the first node on a shared channel that supports transmission of messages using each of the plurality of multi-antenna transmit modes,   according to one of the plurality of multi-antenna transmit nodes, wherein the method further comprises using one and the same down link multi antenna transmit mode for reception by the UE during the RA procedure on the shared channel.