Results 131 to 140 of about 7,335,937 (187)

Capacity of Coherent Frequency-Hop Spread-Spectrum Communications

Proceedings. IEEE International Symposium on Information Theory, 2002
The capacity of a coherent frequency-hopped (C-FH) spread-spectrum system is investigated, The channel comprises an M-ary phase-shift keying (M-PSK) modulator, a frequency hopper with phase-continuous carrier, the transmission medium, a nonideal phase-coherent frequency dehopper, an M-PSK demodulator, and a carrier tracking system.
G. Cherubini, W. Stark
openaire   +1 more source

Optical frequency-hop multiple access communications system

ICC '98. 1998 IEEE International Conference on Communications. Conference Record. Affiliated with SUPERCOMM'98 (Cat. No.98CH36220), 2002
We propose fast optical frequency-hop code division multiple access (FH-CDMA) for high bandwidth local area networks. Encoding and decoding are achieved by tunable fiber Bragg gratings. Frequency hopping offers many advantages compared to the previously proposed optical CDMA multiple access techniques.
Habib Fathallah, Leslie A. Rusch, Sophie LaRochelle   +2 more
openaire   +2 more sources

Sets of Optimal Frequency-Hopping Sequences

IEEE Transactions on Information Theory, 2008
In communication systems, frequency-hopping spread spectrum and direct-sequence spread spectrum are two main spread coding technologies. Frequency-hopping sequences are needed in FH-CDMA systems.
Jianxing Yin
exaly   +2 more sources

Frequency-Hopped Communications

1991
Spread-spectrum communications may also be achieved by using frequency hopping of the RF carrier. Instead of direct-phase shift modulation of a digital sequence onto the RF carrier, as in DS-CDMA, the sequence is used to frequency hop the carrier. In this chapter we examine the basic elements of this type of communication link.
openaire   +1 more source

Adaptive frequency hopping in HF communications

Proceedings of MILCOM '93 - IEEE Military Communications Conference, 1995
Frequency hopping (FH) has been proposed as a technique to combat multipath fading and interference problems in HF links. By means of powerful coding techniques these systems are able to restore the transmitted information also under adverse transmission conditions when several of the frequencies in use are jammed or fading.
openaire   +1 more source

Frequency-Hopping Communication Systems

2003
Abstract : This report presents a current review and analysis of the most important aspects of frequency-hopping communication systems. Frequency synthesis and other implementation issues are discussed. The effects and suitability of various modulations is examined. The impact of error-correcting codes on the performance of frequency-hopping systems is
openaire   +1 more source

The role of frequency hopping in today's digital communications

1988 IEEE 5th International Symposium on Spread Spectrum Techniques and Applications - Proceedings. Spread Technology to Africa (Cat. No.98TH8333), 2002
We investigate the capacity of an OOK FH CDMA channel. We assume random FH codes and that the i-th receiver is only interested in the message transmitted by the i-th transmitter. The degradation of the AWGN and non-selective Rayleigh fading environments on the FH system are also investigated. We then give an algebraic construction of a new family of FH
S. Maric, O. Moreno
openaire   +1 more source

Uplink timing detection for frequency hopping communication

MILCOM 1999. IEEE Military Communications. Conference Proceedings (Cat. No.99CH36341), 2003
In this paper we consider the problem of detecting an uplink time probe of a frequency hopping communication system with uplink partial processing employing symmetric differential phase shift keying (SDPSK) signaling. Analytical and simulation results on the probability of detection error for a probe signal received over multiple hop durations in noise
M.R. Shane, null Hen-Geul Yeh, G.L. Lui, A.H. Yamada   +3 more
openaire   +1 more source

Synchronization Design of Frequency-Hopping Communication System

2018 2nd IEEE Advanced Information Management,Communicates,Electronic and Automation Control Conference (IMCEC), 2018
Frequency hopping is one of the most classic examples of spread-spectrum communications. This paper is about the study of the strategy of the synchronous process. Modern frequency hopping systems generally use the sliding correlation scheme and the matched filter scheme which have the best anti-jamming performance.
Zhao Xiangwu, Quan Houde, Cui Peizhang
openaire   +1 more source

Fundamental limitations on repeater jamming of frequency-hopping communications

IEEE Journal on Selected Areas in Communications, 1989
Fundamental limitations on the effectiveness of repeater jamming are derived. These limitations arise because of the geometry and the need for frequency estimation and signal sorting. Limitations on the hopping rate, which might be increased to counter a repeater-jamming threat, are derived from consideration of practical requirements. >
openaire   +2 more sources