The technology oftime-division multiple-access (TDMA) and code-division multiple-access (COMA) promises to significantly improve the capacity and operation ofexisting analog cellular networks. AT&T has been on the leading edge ofthese breakthroughs, developing trial and commercial systems for both oftheseadvanced digital radio technologies. This paper describes TDMA and COMA, theiradvantages, specific features, field testresults, and speculations ontheirfutures.

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DE-FG22-94MT94014 Southern University Center f o r Energy and Environmental Studies P.O. Box 9764 Baton Rouge, LA 70813 This report was prepared as an account of work sponsored by an agency of the United States Government. Neither the United States Government nor any agency thereof, nor any of their employees, makes any warranty, express or implied, or assumes any legal liability or responsibility for the accuracy, completeness, or usefulness of any information, apparatus, product, or process disclosed, or represents that its use would not infringe privately owned rights. Reference herein to any specific commercial product, process, or service by trade name, trademark, manufacturer, or otherwise does not necessarily constitute or imply its endorsement, recommendation, or favoring by the United States Government or any agency thereof. The views and opinions of authors expressed herein do not necessarily state or reflect those of the United States Government or any agency thereof.

This report was prepared as an account of work sponsored by an agency of the United States Government. Neither the United States Government nor any agency thereof, nor any of their employees, makes any warranty, expressed or implied, or assumes any legal liability or responsibility for the accuracy, completeness, or usefulness of any information, apparatus, product, or process disclosed, or represents that its use would not infringe privately owned rights. Reference herein to any specific commercial product, process, or service by trade name, trademark, manufacturer, or otherwise does not necessari Iy constitute or imply its endorsement, recommendation, or favoring 'by the United States Government or any agency thereof. The views and opinions of authors expressed herein do not necessarily state or reflect those of the United States Government. This report has been reproduced directly Iiom the best available copy.