Stan Vitebsky

Performance and Capacity of Cellular OFDMA Systems With Voice-Over-IP Traffic

We propose a methodology to evaluate the voice-over-IP (VoIP) capacity and performance of orthogonal frequency-division multiple-access (OFDMA)-based systems. The approach combines the queuing and interference analyses to find the delay and power outage. Using this analytical framework, we provide insight into tradeoffs among capacity-limiting factors, including channel dimensions, power, interference threshold and latency, and we identify techniques for capacity optimization. The numerical demonstrations are carried out on the newly standardized ultra mobile broadband (UMB) system. The same methodology can also be applied to Universal Mobile Telecommunications System (UMTS) Long Term Evolution (LTE) and wireless mobile Worldwide Interoperability for Microwave Access (WiMAX) systems.

Performance of 1xEV-DO third-generation wireless high-speed data systems

Wireless high-speed data systems based on 1xEV-DO have recently been deployed commercially and in field trials. In this paper, the emphasis is placed on the validation of the simulated forward link system-level performance through comparison with field data. High spectrum efficiency observed both in simulations and in the field is explained by the salient features of 1xEV-DO that make it suitable for data communications in a cellular mobile environment. These features include, among others, the long-range channel estimation and rate prediction, incremental redundancy hybrid automatic request control (ARQ), turbo coding, and scheduling that exploits multi-user diversity in a fast fading environment. The paper also addresses the reverse link performance and the practical system constraints imposed by the signaling overhead necessary to support high throughput on the forward link.

Forward link performance analysis of the CDMA2000 ∗ 3G1X data system

Performance analysis of data networks based on the code division multiple access (CDMA) air interface including the CDMA2000∗ 3G1X and the Universal Mobile Telecommunications System (UMTS) requires development of new methodologies distinct from those used to analyze voice networks. In this paper, we present a set of analytical and simulation techniques of different complexity that are used to investigate different aspects of data system performance on the forward link. We demonstrate how the static-snapshot simulation model is used to obtain statistically significant system-level results valid for multi-cell wide area network deployment. These simulations are complemented by the dynamic model, which takes into account details of data traffic arrival and resource management algorithms on the air interface. It also provides insight into each individual users experience under different network loads when running different data applications over the CDMA2000 air interface. Key results of simulation models are verified via theoretical analysis techniques that demonstrate the consistency of the results obtained via different methods.

Performance of 1x EV-DO Revision A systems with best effort data and voice over IP

In Revision A of the 1x EV-DO (1x evolution data optimized) standard, a number of enhancements and new capabilities have been introduced. The reverse link supports hybrid automatic repeat request (HARQ) operation and a peak data rate of 1.8 Mbps. The forward link supports short and multi-user packet formats for greater efficiency as well as a peak data rate of 3.1 Mbps. The medium access control (MAC) layer is enhanced to handle multiple application flows with differing latency and error rate requirements simultaneously by providing per-flow quality of service (QoS) guarantees. In this paper, we evaluate 1x EV-DO Revision A forward and reverse link throughput performance improvement for best effort data applications. Further, we study system performance when best effort data shares the bandwidth with delay sensitive QoS applications such as Voice over IP (VoIP) and investigate the implications of their interaction on capacity, voice quality, and aggregate system throughput.

Broadcast-multicast in 1x EV-DO Revision A systems and its application to enhanced mobile services

1x EV-DO (1x evolution data optimized) broadcast-multicast service (BCMCS) enables a host of new applications in the mobility environment. Examples of such applications range from mobile TV broadcasting for the consumer market to supporting conference and “walkie-talkie” group calls for business, government, and public safety users. In this paper, we investigate aspects of BCMCS deployment and performance associated with the support of different applications. Through analysis and simulation, we evaluate BCMCS coverage and capacity in mobile TV broadcast deployment when using various transmission format configurations, such as soft handoff combining, orthogonal frequency division multiplexing (OFDM), and Reed-Solomon coding. We further propose a scheme for maximizing system-wide air interface resource efficiency when BCMCS is used to support wireless group calls. Using a Voice over Internet Protocol (VoIP) group call as an example, we show how the decision strategy for choosing BCMCS vs. unicast could be optimized on the basis of the group size, the geographical distribution of group members, and their mobility.