Decode-and-forward relay beamforming for secrecy with finite-alphabet input

Vishwakarma, Sanjay and Chockalingam, A (2013) Decode-and-forward relay beamforming for secrecy with finite-alphabet input. In: IEEE Communications Letters, 17 (5). pp. 912-915.

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Abstract

In this letter, we compute the secrecy rate of decode-and-forward (DF) relay beamforming with finite input alphabet of size M. Source and relays operate under a total power constraint. First, we observe that the secrecy rate with finite-alphabet input can go to zero as the total power increases, when we use the source power and the relay weights obtained assuming Gaussian input. This is because the capacity of an eavesdropper can approach the finite-alphabet capacity of 1/2 log(2) M with increasing total power, due to the inability to completely null in the direction of the eavesdropper. We then propose a transmit power control scheme where the optimum source power and relay weights are obtained by carrying out transmit power (source power plus relay power) control on DF with Gaussian input using semi-definite programming, and then obtaining the corresponding source power and relay weights which maximize the secrecy rate for DF with finite-alphabet input. The proposed power control scheme is shown to achieve increasing secrecy rates with increasing total power with a saturation behavior at high total powers.

Item Type:	Journal Article
Publication:	IEEE Communications Letters
Publisher:	IEEE
Additional Information:	Copyright of this article belongs to IEEE.
Department/Centre:	Division of Electrical Sciences > Electrical Communication Engineering
Date Deposited:	18 Jul 2013 07:02
Last Modified:	18 Jul 2013 07:02
URI:	http://eprints.iisc.ac.in/id/eprint/46873

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