Method and system for wireless communication networks using relaying

Abstract

The present invention relates to wireless networks using relaying. In the method according to the present invention of performing communication in a two-hop wireless communication network, a transmitter 210, a receiver 220 and at least one relay station 215 are engaged in a communication session. The relay station 215 forwards signals from a first link between the transmitter 210 and the relay station 215 to a second link between the relay stations 215 and the receiver 220. The forwarding performed by the at least one relay station 215 is adapted as a response to estimated radio channel characteristics of at least the first link. Preferably the forwarding is adapted as a response to estimated radio channel characteristics of both the first and second link.

Description

FIELD OF THE INVENTION The present invention relates to relay supported wireless communication to enhance communication performance. In particular the invention relates to a method and a system for performing communication in a two-hop wireless communication network. BACKGROUND OF THE INVENTION A main striving force in the development of wireless / cellular communication networks and systems is to provide, apart from many other aspects, increased coverage or support of higher data rate, or a combination of both. At the same time, the cost aspect of building and maintaining the system is of great importance and is expected to become even more so in the future. As data rates and / or communication distances are increased, the problem of increased battery consumption is another area of concern. Until recently the main topology of wireless networks has been fairly unchanged, including the three existing generations of cellular networks. The topology characterized by the cellular architec...

AI Technical Summary

Benefits of technology

Thanks to the invention it is possible to better adjust the forwarding on the second link to the actual conditions present during a communication session. In addition the forwarding can be better adjusted to changes in the conditions.

One advantage afforded by the present invention is that the more precise and reliable characterization of the individual radio paths may be used to determine and optimize different transmission parameters. Whereby, the capabilities of a cooperative relaying network, for example, may be more fully exploited.

A further advantage is that characterisation of the first and second link advantageously is performed in the relay stations. Hence, the method according to the invention fascilitates a distribution of functionalities in the network allowing an increase in the number of relay stations in a communication session without any significant increase in the amount of protocol overhead that is needed for the transmission of data from the transmitter to the receiver.

A yet further advantage further advantage of the method and system according to the present invention is that the improved characterization of the first and second link facilitate to take full advantage of the anticipated advantages of a network with cooperative relaying that comprises a larger number of relaying stations. With the invention used in a coherent combining setting, the directivity gain and diversity gain increases with increasing number of relay stations. The directivity gain itself offers increased SNR that can be used for range extension and / or data rate enhancement. The diversity gain, increases the robustness of the communication, providing a more uniform communication quality over time. While directivity and diversity gain can be provided by various traditional advanced antenna solutions, where the antennas are placed either at the transmitter or the receiver, the proposed solution is generally not limited to the physical space constraints as is seen in basestations or mobile terminals. Hence, there is indeed a potential to use a larger number of relays, than the number of antennas at a basestation or a mobile station, and hence offer even greater directivity and diversity gains.

Problems solved by technology

This has the consequence that performance may degrade and resources are inefficiently utilized.

Whereby, the prior art has not been able to fully take advantage of the anticipated advantages of a cooperative relaying network.

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