International Business Machines Corporation

The Titan Corporation

Mark J Lindsey

Krishnanand Kelkar

Thomas C Reiner

The present invention is a method and apparatus for providing orthogonal frequency hopping for users in a communication system. The users have user bandwidths allocated on a frequency band. A jitter space is provided with a jitter bandwidth on the allocated frequency band. If at least one of the user bandwidths is larger than the jitter space, a skip zone is determined for at least one of the user bandwidths. The skip zone is unoccupied by a starting hop of the user bandwidths when the user bandwidths are shifted in a frequency hopping.

Orthogonal frequency hopping using skip zones

A decoding system for decoding a digital data stream that has been convolutionally encoded in accordance with a selected constraint length and selected polynomial codes, which system includes a processor, such as a Viterbi decoder, that is reconfigurable so that it can decode encoded digital data streams for a number of different user channels for which data streams have been convolutionally encoded in accordance with respectively different combinations of selected constraint length and selected polynomial codes. The decoding system includes a Viterbi decoder for processing the encoded data stream in accordance with said selected constraint length and in accordance with said selected polynomial codes to decode the encoded data stream; a RAM for storing data of said selected constraint length and data of said selected polynomial codes in accordance with which said data stream was encoded; and a RAM I/O interface circuit responsive to a user channel identification signal for retrieving said selected constraint length data and said selected polynomial code data from the RAM and configuring the Viterbi decoder in accordance with said selected constraint length and said selected polynomial codes. In order to accommodate concurrent multiple user channels, the RAM stores different sets of combinations of constraint length data and polynomial code data corresponding to different user channels, with said different sets being retrievable from the RAM in response to respectively different user channel identification signals. The polynomial code data and constraint length data in the RAM may be changed from time to time in response to software instructions, as user channel requirements change. The Viterbi decoder processes said encoded data stream over a plurality of decoding cycles and produces intermediate decoding results during different decoding cycles; and the RAM I/O interface circuit stores in the RAM said intermediate decoding results produced for each different user channel during the different decoding cycles.

Growing community of inventors

San Diego, CA, United States of America

Mark J Lindsey