Performance of an order statistic based diversity combining frequency-hopping BFSK system in a partial-band jamming environment

Abstract

An order-statistic-based combining technique is evaluated for fast frequency hopping spread spectrum receivers operating in the presence of partial-band noise jamming. The method replaces the linear combining receiver with an outlier-resistant estimator based on order statistics. It is applicable to noncoherent frequency shift keying modulation, at the expense of sorting and linear combining in each of the channels. Two different receiver designs are examined, one has separate pseudorandom (PN) codes for each of the channels, while the other receiver structure uses a single PN code leading to a contiguous jamming environment. The performances of both the linear combining and order-statistic-based receivers, including thermal noise, are evaluated and compared when operating in either a contiguous or independent partial-band jamming environment. The probability of a bit error is evaluated for both a selection of a single order statistic and a linear combination of the sum of the 1/sub st/ to K/sub th/ smallest from a sample of L hops/b. A diversity combining gain is realized, and a practical algorithm is advocated which sums all but the largest of the received hops.<>