Spectral Efficient OFDM-FH/SSMA Packet Radio System

Period of Performance: 12/23/1998 - 06/23/1999


Phase 1 SBIR

Recipient Firm

Moriah Technologies, Inc.
P.O. Box 9104
McLean, VA 22102
Principal Investigator

Research Topics


The objective of this project is to devise an innovative frequency hopping spread spectrum digital packet radio modulation technology for transmitting high bit rate data using spectrally efficient information signals. The system introduces a number of innovations including: the use of orthogonal frequency division multiplexing as the baseband modulation strategy, single-sideband as the RF modulation strategy, and turbo trellis-coded modulation as the channel encoding forward error correction scheme. Orthogonal frequency hopping spread spectrum will be used to provide a multi-access strategy, secure communications, and high immunity to frequency selective multipath fading and interference. Communications, synchronization, and acquisition is acquired on a packet-by-packet basis. The proposed scheme encodes M-ary pilot-based synchronization information in parallel with the data in reserved frequency sub-channels. These pilots are the basis of channel estimation and equalization. The signal constellation is coherent quadrature amplitude modulation (QAM), which enables the modulator to operate with spectrum efficiencies greater than 2 bits/sec/Hertz at nominal clock rates, minimal power consumption, and a low probability of error. Integrating the modulation concept with an advanced packet control scheme allows the allocation of bandwidth-on-demand which enables supplying programmable voice, graphical, audio, data, and video services. The objective of this packet radio technology is to permit operations in dynamic, interactive multi-band, multi-user, multi-access, and multi-services modes. BENEFITS: For military markets, the proposed technology is designed for Battlefield Information Transmission System (BITS) applications. In terms of private sector markets, the technology will be employed to develop wireless telecommunication systems in the U-NII and LMDS bands. Commercialization will occur through internal production and technology licensing agreements.