Coded FH/SS Communications in the Presence of Combined Partial-Band Noise Jamming, Rician Nonselective Fading and Multi-User Interference
Coded FH/SS Communications in the Presence of Combined Partial-Band Noise Jamming, Rician Nonselective Fading and Multi-User Interference

Author:

Publisher:

Published: 1987

Total Pages: 65

ISBN-13:

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In this paper we address the problem of combating combined interference in spread-spectrum communication links. We consider frequency-hopped spread-spectrum systems with M-ary FSK modulation and noncoherent demodulation which employ forward-error-control coding. The interference consists of partial-hand noise jamming, nonselective Rician fading, other-user interference and thermal noise. The coding schemes which we analyze include: Reed-Solomon codes (with or without diversity and error-only; erasure-only or parallel erasure/error decoding), binary, nonbinary, and dual- k convolutional codes with and without side information (information about the state of the channel), and concatenated schemes (Reed-Solomon outer codes with either inner detection-only block codes or inner convolutional codes). In all cases we derive (i) the minimum signal-to-jammer energy ratio required to guarantee a desirable bit error rate as a function of p, the fraction of the band which is jammed, when the number of interfering users is fixed, and (ii) the maximum number of users that can be supported by the system as a function of p, when the signal-to-jammer energy ratio is fixed.

Coded FH/SS (Frequency-Hopped Spread-Spectrum) Communications in the Presenceof Combined Partial-Band Noise Jamming, Rician Nonselective Fading, and Multiuser Interference
Coded FH/SS (Frequency-Hopped Spread-Spectrum) Communications in the Presenceof Combined Partial-Band Noise Jamming, Rician Nonselective Fading, and Multiuser Interference

Author: Evaggelos Geraniotis

Publisher:

Published: 1987

Total Pages: 34

ISBN-13:

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In this report, we address the problem of combatting combined interference in spread-spectrum communication links. We consider frequency-hopped spread-spectrum systems with M-ary FSK modulation and noncoherent demodulation that use forward-error control coding. The interference consists of partial-band noise jamming, nonselective Rician fading, other-user interference, and thermal noise. The coding schemes that we analyze include: Reed-Solomon codes (with or without diversity and error/only), erasure-error or parallel erasure/error decoding); binary, nonbinary, and dual-k convolutional codes with or without side information (information about the state of the channel); and concatenated schemes (Reed-Solomon outer codes with either inner detection-only block codes or inner convolutional codes). In all cases, we derive the minimum signal-to-jammer energy ratio required to guarantee a desirable bit error rate as a function of the fraction of the band that is jammed when the number of interfering users is fixed, and the maximum number of users that can be supported by the system as a function of the fraction of the band that is jammed, when the signal-to-jammer energy ratio is fixed. (Author).

Performance Analysis of Coded Frequency-Hopped Spread-Spectrum Systems with Unknown Interference
Performance Analysis of Coded Frequency-Hopped Spread-Spectrum Systems with Unknown Interference

Author: M. V. Hedge

Publisher:

Published: 1987

Total Pages: 117

ISBN-13:

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Two classes of problems are considered. In the first class we model the process of communicating in the presence of interference, which is unknown or hostile, as a two-person zero sum game with the communicator and the jammer as the players. The objective functions we consider are mutual information and the channel cutoff rate. The communicator's strategies are distributions on the input alphabet and on a set of quantizers and the jammer's strategies are distributions on the noise power subject to certain constraints. We consider various conditions on the jammer's strategy set and on the communicator's knowledge. For the case with the decoder uninformed of the actual quantizer chosen, we show that, from the communicator's perspective the worst-case jamming strategy is a distribution concentrated at a finite number of points thereby converging a functional optimisation problem into a nonlinear programming problem. Moreover, we are able to also characterize the worst-case distributions by means of necessary and sufficient conditions which are easy to verify. For the case with the decoder informed of the actual quantizer chosen we are able to demonstrate the existence of saddle-point strategies.