Recently the requirement for wireless ad hoc networks to support multimedia services like videoconference and VOD has become more and more urgent, and load balancing is recognized as an effective mechanism to satisfy the real-time requirements of these services. But many current ad hoc routing protocols are single-path and best-effort routing, which aren't fit for load balancing. In this paper a node-disjoint multi-path routing protocol, namely Enhanced Multi-path Routing (EMR), is first presented to fulfill the short end-to-end delay and low package loss rate requirements of real-time traffic. Then the policy of how to balance load over multiple paths is discussed based on EMR in the paper. According to some key factors that can affect the performance of load balancing, a load-balancing weight (LBW) equation is formed to describe our load-balancing algorithm quantitatively. The simulation results indicate that the proposed load-balancing mechanism decreases the end-to-end delay and the packet loss rate of real-time traffic.
Proc. SPIE. 5284, Wireless Communications and Networks
KEYWORDS: Electronics, Adaptive optics, Control systems, Numerical analysis, Chlorine, Wireless communications, Electronics engineering, Algorithm development, Performance modeling, Global system for mobile communications
Due to scarce radio bandwidth, efficient mobility management method is necessary for the PCS. This paper presents a new mobility management method for the PCS networks. It consists of three parts: cell coding scheme, location update strategy and paging strategy. The cell code scheme, which provides information about the topology of the network to mobile terminals, is the basis for the location update strategy in this paper. The location update strategy is a simplified derivative of distance-based scheme. An adaptive distance threshold is obtained by exploiting the mobile terminal’s individual call and mobility pattern. Since the location update strategy is not designed for certain mobility model such as random walk or fluid flow model, the computation of distance threshold is not only simplified but also better matches the real moving behavior of different mobile terminals. The paging strategy in this method is two-step. The moving direction vector is introduced here to optimize the paging procedure. Two-step paging will significantly reduce the signaling cost for paging. And it can be easily generalized to multi-step paging within the call setup delay constraint. A numerical analysis between mobile terminals with various moving and call patterns is provided. The mobility management method helps optimize the location update cost for all kinds of users.
During the distributed design of UMTS-SGSN system, the Dynamic Central Tasks Scheduling algorithm (DCTS) with good real-time property is researched to meet the hard requirements of bandwidth and latency of UMTS-SGSN system. Based on the assumption without task migration, Markov queuing network model is used to model UMTS-SGSN system instead of M/M/c queuing model. For single user with one PDP context, DCTS is optimal through the theoretic calculation and simulation. And for single user with not less than one PDP context, the performance of DCTS is discussed through the simulation. In the case of longer service time in data service, DCTS is compared with stochastic scheduling algorithm and cycle scheduling algorithm. Simulation results show that DCTS is better than other two algorithms, and when service time is shorter, three algorithms' performance is approximately same. The performances of the three algorithms in different service time are also analyzed by adjusting the parameter μ of the exponential distribution. Results show that exponential distribution's heavy-tailed effect of the service time leads to deteriorating the efficiency of load balancing and DCTS shall initiate less task migration and decrease system overhead.
In this paper, an existing protocol, i.e. TRIP (Telephony Routing over IP) is developed to provide distributed QoS when making resource reservations for VoIP services such as H.323, SIP. Enhanced LSs (location servers) are deployed in ITADs (IP Telephony Administrative Domains) to take in charge of intra-domain routing policy because of small propagation price. It is an easy way to find an IP telephone route for intra-domain VoIP media association and simultaneously possess intra-domain load balancing features. For those routing reservations bridging domains, inter-domain routing policy is responsible for finding the shortest inter-domain route with enough resources. I propose the routing preference policy based on QoS price when the session traffic is shaped by a token bucket, related QoS messages, and message cooperation.