There is a limited amount of RF spectrum that has been allocated by the FCC to cellular communications (800-900 MHz and 1.8-2.0 GHz). To increase capacity, the only alternatives available, in lieu of increasing available RF spectrum, are to invent new technology or to more efficiently use the currently available technology. The Telecommunication Industry Association (TIA) has standardized CDMA as TIA Interim Standard 95 (IS-95). IS-95 systems can carry about 10-15 times as many voice calls as an analog system in the same spectrum. It is well known that voice communications consists of both talkspurts and silent periods. Talkspurts consist of only 40 percent of the call, the remaining 60 percent of the call is silence. The authors are studying the reallocation of silent periods to a lower grade of data users in an attempt to integrate voice and data users in a CDMA system and to maximize use of the available RF spectrum.

Two-layer encoding of packet video may be a useful way to minimize network resource usage while coping with potential packet loss. A two-layer codec architecture modeled after the H.261 RM8 algorithm is proposed, and is shown to be a generalization of the requantization and spectral separation encoding techniques. Experiments were performed using two ten-second video sequences to examine the efficiency of two-layer encoding algorithms. Three techniques: periodic group of blocks (GOB) replenishment, conditional macroblock replenishment, and block error thresholding, are shown to improve the efficiency of two-layer encoding. A hybrid encoding method utilizing both spectral separation and requantization is shown to provide the best results.>

Broadband ATM networks at multi-megabit data rates will provide the necessary bandwidth for high-quality interactive video applications. Performance requirements for high-quality video services are introduced. Results of statistical simulations of broadband networks transmitting video signals are shown to demonstrate that VBR coding provides gains in multiplexed channel utilization and in access link capacity. Issues relating to protocol design for ATM networks, particularly congestion control and error control, are introduced. Various techniques for handling cell loss are compared.>

The topology described applies to any general-purpose computer networking environment. The scheme is named the spiral topology because the architecture is built around modules of four computer nodes each, connected by top and bottom spirals. The spiral technology features a simple internal self-routing algorithm that adapts quickly and automatically to failed nodes or links. The six most important direct consequences of the network architecture are the topology's: (1) ease of expansion; (2) fast, on-the-fly self-routing; (3) extremely high tolerance to network faults; (4) increased network security; (5) potential for the total elimination of store-and-forward transmissions due to routing decision delays; and (6) rendering the maximum path length issue moot.>