Adjacent-Channel Interference in Frequency-Hopping Ad Hoc Networks

TL;DR

This paper analyzes the impact of adjacent-channel interference in frequency-hopping ad hoc networks using CPFSK, providing expressions for outage probability and transmission capacity, and identifying optimal fractional in-band power for maximizing capacity.

Contribution

It offers a new comprehensive analysis of ACI effects in frequency-hopping networks, including optimal fractional in-band power determination.

Findings

Derived expressions for outage probability and transmission capacity.

Identified the optimal fractional in-band power for maximum capacity.

Accounted for shadowing, fading, and network parameters in the analysis.

Abstract

This paper considers ad hoc networks that use the combination of coded continuous-phase frequency-shift keying (CPFSK) and frequency-hopping multiple access. Although CPFSK has a compact spectrum, some of the signal power inevitably splatters into adjacent frequency channels, thereby causing adjacent-channel interference (ACI). The amount of ACI is controlled by setting the fractional in-band power; i.e., the fraction of the signal power that lies within the band of each frequency channel. While this quantity is often selected arbitrarily, a tradeoff is involved in the choice. This paper presents a new analysis of frequency-hopping ad hoc networks that carefully incorporates the effect of ACI. The analysis accounts for the shadowing, Nakagami fading, CPFSK modulation index, code rate, number of frequency channels, fractional in-band power, and spatial distribution of the interfering mobiles. Expressions are presented for both outage probability and transmission capacity. With the objective of maximizing the transmission capacity, the optimal fractional in-band power that should be contained in each frequency channel is identified.