A Hybrid Error Control Scheme for MANET Reliable Multicast Abstract This paper focuses on the reliable multicast in mobile ad hoc networks (MANETs), which is crucial for military and disaster rescue scenarios. Different from previous work, in this paper we introduce a new hybrid error control scheme that integrates interleaving, forward error correction (FEC), and automatic repeat request (ARQ) to mitigate the error and loss effects encountered in MANETs. To evaluate the performance of this scheme, mathematical analysis is conducted carefully. Numerical results from mathematical analysis show that this new hybrid error control scheme has shorter data transmission delay and less packet loss rate than the MANET multicast algorithm who only employs ARQ. Keywords: Hybrid error control; MANET reliable multicast. 1 Introduction In the previous literature, mainly two approaches, the automatic repeat request (ARQ) and the anonymous gossip (AG), were suggested as packet recovery mechanisms to counteract packet loss and error in mobile ad hoc networks (MANETs) [1,2]. However, these two approaches have long data transmission latency, and are not suitable for delay sensitive applications. Different from previous work, in this paper we introduce a new hybrid error control scheme that integrates interleaving, forward error correction (FEC), and ARQ to mitigate the error and loss effects encountered in MANETs. In order to work compatibly with a verity of MANET multicast routing protocols, this new scheme is based on Client/Server architecture, and resides on the top of UDP layer. To give a clear description of this hybrid error control scheme, we use specification and description language (SDL) [3] to formally depict it from a broad overview down to detailed design levels. In addition, mathematical analysis is conducted carefully to evaluate the performance of this scheme. The rest of the paper is organized as follows. Firstly, we introduce the SDL modeling of hybrid error control scheme for MANET reliable multicast in Section 2. Then, the mathematical analysis of this scheme is presented in Section 3. Finally, Section 4 summarizes our results. 2 SDL Modeled Hybrid Error Control Scheme for MANET Reliable Multicast 2.1 SDL Modeling SDL is utilized to formally model the hybrid error control scheme for MANET reliable multicast. The new hybrid error control scheme is based on Client/Server architecture, and its main entities are the server and client algorithms which reside on top of the Internet UDP layer. The server routine typically exists at the sender of video/audio multicast or one of the intermediate routers (called domain receiver or DR in multicast terminology). The client routine exists at the end user or the receiver part of DR. As an outline, Fig.1 shows the system model of this hybrid error control scheme. Furthermore, the algorithms running on the server side and client side are depicted by FSMs in Fig.2 and Fig.3 respectively. Fig. 1. System model of the hybrid error control scheme for MANET reliable multicast Fig. 2. Server FSM Ahmed K. Elhakeem Department of Electrical and Computer Engineering Concordia University Montreal, Quebec, Canada, H3G 1M8 Bo Rong, Kais Mnif, Michel Kadoch LAGRIT, Department of Electrical Engineering Ecole de technologie superieure, Universite du Quebec Montreal, Quebec, Canada, H3C 1K3 0-7803-8886-0/05/$20.00 ©2005 IEEE CCECE/CCGEI, Saskatoon, May 2005 1086 Authors Absent - Paper Not Presented