Wireless communications apparatus, a method and a communication system for performing relay selection

摘要

The embodiments relate to a wireless communications apparatus configured to operate as one of a source node, a relay node or a destination node in a network comprising a plurality of source nodes, relay nodes and destination nodes configured to support dual-hop communication using one of said relay nodes to intercede between one of said source nodes and one of said destination nodes, and a method for selecting a relay node. The wireless apparatus is configured to collect channel characteristics between the intended source node and each relay node, and between each relay node and the intended destination node, and select a relay node for relaying a signal emitted by the intended source node by determining a mode of operation for performing the selection on the basis of collected channel characteristics. The wireless communication apparatus is further configured to change the mode of operation to a different one if the channel characteristics change. The mode of operation of performing the relay node selection is one of a first mode and a second mode. In the first mode; the relay node is selected on the basis of said channel characteristics between the intended source node and each relay node and in the second mode; the relay is selected on the basis of said channel characteristics between each relay node and the intended destination node.

主权项

1. A wireless communications apparatus configured to operate as one of a source node, a relay node or a destination node in a network comprising a plurality of source nodes, relay nodes and destination nodes, said network configured to support dual-hop communication using one of said relay nodes to intercede between one of said source nodes and one of said destination nodes, the apparatus comprising:
a decision node operable to determine a mode of operation for selecting a relay node to relay a signal emitted by an intended source node, the decision node being operable to determine said mode of operation on the basis of channel characteristics including statistical channel information collected from a collecting node, and further operable to change the determined mode of operation to a different mode in the event that the channel characteristics change; said mode of operation for selecting the relay node being one of a first mode and a second mode, where in the first mode, said relay node is selected on the basis of channel characteristics between the intended source node and each relay node, and in the second mode, said relay node is selected on the basis of channel characteristics between each relay node and an intended destination node; wherein said decision node is operable to determine that the mode of operation is the first mode in the event that a criterion is satisfied, and to otherwise determine that the mode of operation is the second mode, and is further operable to switch from the first mode to the second mode in the event that said criterion is no longer satisfied or to switch from the second mode to the first mode in the event that said criterion is satisfied; wherein when all channels experience Nakagami-m fading, the criterion is given by: if d1>d2 then the mode of operation is determined as the first mode by the decision node, otherwise the mode of operation is determined as the second mode; where d1 and d2 are the diversity orders due to the first mode and second mode respectively, and are given by:d1=min⁢⁢(∑n=1N⁢⁢m1⁢n,m21,m22,…⁢⁢m2⁢N)d2=min⁢⁢(∑n=1N⁢m2⁢n,m11,m12,…⁢⁢m1⁢N) where N is the number of relay nodes that can be selected, and m1n, m2n, are the shaping parameters of Nakagami-m fading channels to or from the nth relay, respectively, such that the mode of operation that provides a larger diversity gain is performed.