There are only a few multiple target families of Costas and sonar arrays with perfect correlation property. In this paper using the Welch Costas array and some results from design theory we construct perfect auto and cross-correlation families of sonar and extended Costas arrays

We give an algebraic construction for a new family of frequency-hop codes. The construction is based on properties of finite fields: it is shown that for each field GF(p/sup m/), there exists a large number of codes of length p/sup m/. The codes are also shown to possess the best possible simultaneous two-dimensional autocorrelation and cross-correlation properties. Moreover, they include a family of codes: with a code length of a power of 2, which are ideally suitable for applications in digital communication systems.

An adaptive coding scheme is introduced for a discrete sequence code-division multiple-access system. The system uses noncoherent M-ary orthogonal modulation with RAKE receiver and power control. Both a fast fading channel and a combined fast fading, shadowing and power control channel are considered. Analytical bounds and simulations are done to evaluate the performance of the system. It is found that there is significant improvement in the average throughput and the bit-error-rate performance in the adaptive coding scheme. The amount of improvement drops with the increase of diversity branches used. More importantly, it is found that adaptive coding scheme is relatively robust to shadowing, while fix-rate codes are ineffective in the shadowing environment. Finally, adaptive coding scheme is found to be robust to mobile speed, feedback delay, and finite interleaving depth.

This correspondence investigates and compares the capacities of two types of frequency-hopped code-division multiple-access (FH-CDMA) communications systems; namely, multilevel on-off keying (OOK) and MFSK, in particular BFSK. In our multiuser channel model, we assume a random hopping pattern is used for each transmitter-receiver pair, and that the ith receiver is only interested in the message transmitted by ith transmitter. The degradation in AWGN and nonselective Rayleigh fading environments of both types of FH systems is also investigated and compared.

A construction of a new family of optical orthogonal codes (OOCs) for use in code division multiple access (CDMA) fiber-optic networks is given. Previous families of OOCs are reviewed and basic requirements for successful implementation of the fiber-optic CDMA system given. The new code construction is based on Costas (1970) arrays and the codes are proved to be (/spl omega/(2p-3), /spl omega/, 1, 1), p a prime and /spl omega/*Q/spl les/p-1, where Q is the maximum number of users, OOCs. The probability of error (using the Gaussian approximation) in the multiuser system as a performance measure is calculated and compared with that of existing OOCs. The size of the code family is compared against the Johnson bound.>

The problem of the algebraic construction of a particular family of optical codes for use in code-division multiple-access (CDMA) fiber-optic local area networks (LANs) is treated. The conditions that the code families have to satisfy when used in such systems are reviewed. The new codes are called quadratic congruence codes, and the construction of the corresponding sequences is based on the number-theoretic concept of quadratic congruences. It is shown that p-1 codes exist for every odd prime p and can serve as many as p-1 different users in the CDMA fiber-optic system. The codes belong to the family of optical orthogonal codes, their auto- and cross-correlation properties are established, and their performance is compared to that of the previous optical codes. Examples of the codes and examples of their auto- and cross-correlation functions are given.>

The problem of constructing frequency hop codes for use in multiuser communication systems such as multiple-access spread-spectrum communications and multiuser radar and sonar systems is addressed. Previous frequency hopping techniques are reviewed. The construction of a new family of frequency hopping codes called hyperbolic frequency hop codes is given. The concepts of multiple-access spread-spectrum communication systems and multiuser radar and sonar systems are reviewed, and it is shown that the hyperbolic frequency hop codes possess nearly ideal characteristics for use in both types of system. Specifically, in multiple-access communications the codes achieve minimum error probability, while in radar and sonar systems the codes have at most two hits in their auto- and cross-ambiguity function. Examples of address assignment for multiple-access communications systems and radar and sonar auto- and cross-ambiguity functions are also given.>

The cross-ambiguity properties of Costas-array frequency-hop coded signals for use in wideband multiuser sonar systems are established. In order to prevent system crosstalk, cross-ambiguity function for the signals should be minimized. The conditions under which Costas arrays achieve the minimum value of their cross-ambiguity functions are provided. The upper bound on the maximum number of hits in the cross-ambiguity function for Welch-Costas arrays is given, and it is shown that the maximum number of hits depends on the form of the prime over which the arrays are constructed.>