Cross-talk cancellation in cooperative wireless relay networks

#This invention relates generally to wireless relay networks, and more particularly to canceling cross-talk in cooperative wireless relay stations.

#In wireless networks, a base station (BS) is usually located near the center of a cell. As a result, the quality of signals received at a mobile station (MS) near an edge of the cell is reduced. This problem can be resolved by decreasing the size of the cell. However, this increases costs because the number of BSs needs to be increased to provide the same service for the same coverage area. In addition, this also may cause higher level of interference to MSs residing at the edge of neighboring cells. An alternative solution uses a less complex relay station (RS), which assists in communications between the BS and the MS. The RS can effectively increase coverage and reliability with decreased transmit power and cost.

#The RS can be deployed anywhere in the cell wherein direct communication between the BS and the MS is impaired. The RS can also be deployed temporarily in areas where the number of MSs is expected to increase dramatically for a short time period, e.g., large-scale public events.

#FIG. 1 is a schematic of a cooperative relay network operating according to the embodiments of the invention;

#FIG. 2 is a schematic of the cross-talk interference at a relay station operating in the network of FIG. 1 according to the embodiments of the invention;

#FIG. 3 is a flow diagram of a cross-talk cancellation method according to embodiments of the invention;

#Relay Network

#FIG. 1 shows a cooperative relay network 100 operating according to the embodiments of the invention. The wireless network can be a local area network (LAN), a metropolitan area network (MAN), or a large-scale cellular network. The network includes a base station (BS) 101, a relay station (RS) 102, and a mobile station (MS) 103. There can be multiple RSs and MSs. The BS is stationary, and the RSs can be fixed, moving occasionally (nomadic), or mobile. The MS are typically mobile. In the cooperative network, the RS operates as a repeater and communicates signals 105 between the BS and the MSs, or the BS and the MSs communicate directly.

#The RS operates as a frequency-reuse-relay-station (FRRS), or as a frequency-shifted-relay-station (FSRS). The RS can cooperate by using the identical frequency band for receiving and transmitting. Thus, depending on the specific cooperative scheme applied, there can be direct communication links 104 between the BS and the MS, as well as the indirect links 105 so as to achieve cooperation.