In this letter, we present a new method of alleviating the deterioration in the quality of real-time video service during vertical handover (VHO). The proposed method stochastically delays the starting time of the service disruption of VHO in order to reduce the number of lost frames caused by the inter-frame dependency of multi-layered video traffic. The results show that the proposed method significantly decreases the average frame loss time at the sacrifice of an increased handover execution time by one half of the group of picture (GOP) interval of the video traffic.

Hierarchical constellations offer a different property of robustness to the multiple bits that construct a symbol according to channel errors. We apply the characteristics of hierarchical constellations to a multi-user cellular system that has limited modulation levels, in order to improve cell capacity. We propose an adaptive resource allocation scheme based on the hierarchical constellation in which a symbol is shared by multiple users and each bit in a symbol is allocated adaptively according to the channel condition of each user. The numerical results show that the proposed resource allocation scheme provides mobile users with higher modulation levels so that the cell capacity is improved.

In this letter, we propose an energy-aware source routing protocol for maximizing the network lifetime in mobile ad hoc networks. We define a new routing cost by considering both transmit and receive power consumption and remaining battery level in each node simultaneously and present an efficient route discovery procedure to investigate the proposed routing cost. Intensive simulation verifies that the proposed routing protocol has similar performance to the conventional routing protocols in terms of the number of transmission hops, transmission rate, and energy consumption while significantly improving the performance with respect to network lifetime.

In this paper, we analyze the performance of a bulk handoff scheme for mixed traffic in integrated voice/data wireless mobile networks in which new and handoff voice/data calls are accepted based on prioritization of handoff requests. If fewer channels than handoff calls are available in the target cell, some handoff calls are terminated without queuing. A higher priority is given to voice handoff calls than to data handoff calls. A multidimensional birth-death process model is presented to analyze the bulk handoff performance of mixed traffic. A numerical analysis of system performance is presented to evaluate the blocking probabilities of new voice and data calls, handoff failure probabilities, and the forced termination probabilities of voice/data handoff calls.

We propose a power-saving mechanism (PSM) specific to request-and-response-based applications, which simply changes the order of the operating procedure of the legacy PSM by considering the attributes of the request-and-response delay. We numerically analyze the PSM with respect to the energy consumption and buffering delay and characterize this performance by employing a simple energy-delay trade-off (EDT) curve that is determined by the operating parameters. The resulting EDT curve clearly shows that the proposed PSM outperforms the legacy PSM.

A Virtual Cellular Network (VCN) is a wireless cellular network wherein a single Mobile Station (MS) can communicate simultaneously with more than one Base Station (BS). In this paper, we analyze handoff for two kinds of VCN: a 'Distributed Resource-control VCN' (DR-VCN) and a 'Centralized Resource-control VCN' (CR-VCN). A VCN can take advantage of the fact that the same data is received by multiple base stations. The DR-VCN is a system in which every BS controls its own channels, while the CR-VCN is a system wherein a central station controls all system channels. Results from analysis and simulation show that both the new call drop rate and handoff refusal rate of the CR-VCN are much lower than those of the DR-VCN.

CPCH is an uplink common channel that is used by 3GPP to support reliable packet transport. In this paper, we propose a new access scheme by using the discrimination of backoff timer for providing a prioritized service. We also present a simple system model of CPCH for EPA and use it to derive mathematical results. The results show that multi-class services with different priorities can be served effectively and easily by the proposed scheme.