Power control for dynamic packet assignment in advanced cellular Internet service

Wireless broadband networks are expected to employ packet access with high peak-bandwidth demands. This will impose a significant challenge for frequency reuse, especially for the case of ubiquitous services deployed in a wide area. A dynamic packet assignment (DPA) method has been proposed as a key component of the MAC protocol for an OFDM-based advanced cellular Internet service (ACIS) system, which is targeted for applications such as Web browsing, with a peak downlink transmission rate on the order of 1 Mb/s using a wide-area cellular infrastructure. This method is able to allocate radio resources on a packet time scale and reassign them in less than 100 msec, thereby gaining advantages in both statistical multiplexing of packet access and spectrum efficiency of dynamic channel assignment (DCA). One way to achieve very high spectrum efficiency is by using closed-loop SIR-based power control. This paper studies the implementation and performance of various power control methods for DPA in the ACIS environment. It is found that several iterations are required, upon changes of co-channel interference, to update the transmit powers for all active links in order to achieve desirable improvement. However, for a system having many data terminals with short duty cycles, significant overhead may be required for iterative power control. Alternative techniques such as interference suppression, which does not require high iteration overhead, may be attractive options