John M Smith

Efficient Signaling for VoIP in OFDMA

Voice over Internet protocol (VoIP) will be commonplace in future wireless standards. Due to the potentially large number of VoIP users in a wireless system, the overhead associated with controlling VoIP transmissions can hinder system performance, unless it is carefully managed. This paper outlines current efforts in B3G (beyond 3G) standards development to efficiently control VoIP transmissions by grouping VoIP users into scheduling groups, assigning the group a set of shared time-frequency resources, and using bitmap signaling to allocate resources. System level simulations are used to validate the signaling technique and show that the technique can efficiently support 93 users per megahertz. Potential further improvements are described.

Multiple User Packet Repackaging

Revision A of the cdma2000 High Rate Packet Data (HRPD) Air Interface Specification includes a method to serve multiple users in a single packet (3GPP2, 2004), This method is know as medium access control (MAC) layer multiplexing and can facilitate up to 8 users in one packet. It allows Revision A of HRPD to be more effective, when compared to previous revisions of HRPD, in delivering real time applications such as voice, video, and gaming due to the latency improvement. This paper examines the impact on system capacity that results from a proposed technique whereby MAC layer multiplexed transmissions can be terminated prematurely once a certain number of the target receivers have successfully decoded the transmission. It was found that system capacity could be improved by up to 5.8%.

WLC09-4: System Level Performance of HRPD Revision B

Revision B of the high rate packet data standard defines several new transmission formats for forward traffic channel transmission. The new transmission formats provide higher order modulation, an increased quantization in nominal data rate, and more opportunity for hybrid automatic repeat request gain. Consequently, the access terminal has many more choices when mapping a measured pilot signal-to-noise ratio to a requested transmission format. Ultimately, the new transmission formats result in a more efficient use of system resources leading to increased system performance. In this paper, we show that system level performance is increased by 25% for one receive antenna and 28% for two receive antennas as a result of the new transmission formats. We further show the distribution of selected transmission formats.