Search

Opportunity driven multiple access (ODMA), a cellular multihop method proposed for Universal Mobile Telecommunications Systems, potentially allows reduction in power consumption of user equipment (UE), extending Node B's coverage and supporting higher user data rate. However, ODMA requires extra power for discovering relaying nodes and introduces additional transmission latency in data transfer. This paper offers enlightenment to these ODMA implementation problems. A power-efficient routing (PER) mechanism is proposed to identify a minimum-power path for ODMA communication. Prior to the route (or path) discovery, the PER mechanism utilizes an analytical solution to estimate the total power and number of intermediate UEs required in the minimum-power path. With the estimation, route discovery procedures originating from nonattainable ODMA requests can be prevented. For those attainable ODMA requests that require a route discovery procedure to locate intermediate UEs, the PER mechanism further provides a method to set the transmission power and maximum hop count. Hence, the power consumption of each UE during route discovery is significantly reduced. Simulation results coincided with the analysis, and the results demonstrate the performance improvement of PER over dynamic source routing. [ABSTRACT FROM AUTHOR]

We present a traffic-scheduling framework that can dynamically allocate radio resources to a general packet radio service (GPRS) mobile station (MS) based on the interference levels of the radio links and the quality of service (QoS) specification of the MS. The underlying idea of this scheduling scheme is to preserve more bandwidth for use by those MSs that are within a low interference region so that the limited radio resources can be used more effectively. In this scheme, an MS uses a low transmission rate for data transfer when the MS is within a high interference region to avoid wasting bandwidth by transmitting data in a condition with high interference. In order to compensate for the service loss of the MS, we allocate more bandwidth to the MS when it is within a low interference region. In addition, we also propose an analytical model that can be used to derive the transmission rate for an MS in a low interference region based on the delay-bound requirement of the MS. The performance results show that our dynamic scheme can utilize the bandwidth more effectively to satisfy various QoS requirements of the MSs in the GPRS system without changing the convolution-coding rate. [ABSTRACT FROM PUBLISHER]

Provides information on the proposal of a power-spectrum-based connection admission controller design in asynchronous transfer model (ATM) switches for multimedia communications. Information on system configuration and input power-spectrum; Detailed information on power-spectrum-based connection admission control; Conclusion reached.

This work presents an improved wireless token ring protocol (IWTRP) for wireless metropolitan area networks (W-MANs) adopting a ring topology. Opposed to the single token and transmission permitted in WTRP, IWTRP provides a novel method to allow for multiple tokens, and thus multiple simultaneous transmissions in the ring. IWTRP employs both the request-to-send/clear-to-send (RTS/CTS) handshaking and the network allocation vector (NAV) updating techniques to resolve collision-resolution and token-elimination problems resulted from multiple tokens. The normalized saturation throughput of IWTRP is analytically characterized and verified through simulations. [ABSTRACT FROM PUBLISHER]

This work presents a wireless token-passing protocol, named Ripple, for wireless mesh networks (WMNs). In contrast to existing random-access approaches, Ripple uses a decentralized controlled-access approach to protect nodes from unintentional packet collisions and maximize the spatial reuse. The performance of Ripple under an error-free wireless channel was investigated and the accuracy of the analysis was verified by simulation. Simulation results also indicated that Ripple achieved throughput, stability, and QoS enhancement than that of 802.11 DCF under a highly loaded situation [ABSTRACT FROM PUBLISHER]