  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.
