Stable throughput of cognitive radios with and without relaying capability

Document Type

Article

Publication Date

12-1-2007

Abstract

A scenario with two single-user links, one licensed to use the spectral resource (primary) and one unlicensed (secondary or cognitive), is considered. According to the cognitive radio principle, the activity of the secondary link is required not to interfere with the performance of the primary. Therefore, in this paper, it is assumed that the cognitive link accesses the channel only when sensed idle. Moreover, the analysis includes: 1) random packet arrivals; 2) sensing errors due to fading at the secondary link; 3) power allocation at the secondary transmitter based on long-term measurements. In this framework, the maximum stable throughput of the cognitive link (in packets/slot) is derived for a fixed throughput selected by the primary link. The model is modified so as to allow the secondary transmitter to act as a "transparent" relay for the primary link. In particular, packets that are not received correctly by the intended destination might be decoded successfully by the secondary transmitter. The latter can, then, queue and forward these packets to the intended receiver. A stable throughput of the secondary link with relaying is derived under the same conditions as before. Results show that benefits of relaying strongly depend on the topology (i.e., average channel powers) of the network. © 2007 IEEE.

Identifier

51149114338 (Scopus)

Publication Title

IEEE Transactions on Communications

External Full Text Location

https://doi.org/10.1109/TCOMM.2007.910699

ISSN

00906778

First Page

2351

Last Page

2360

Issue

12

Volume

55

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