End-to-end support for statistical quality of service in heterogeneous mobile ad hoc networks Jamal N. Al-Karaki, Ahmed E. Kamal * Laboratory for Advanced Networks (LAN), Department of Electrical and Computer Engineering, Iowa State University, Ames, IA 50011-3060, USA Received 29 July 2004; accepted 29 July 2004 Available online 21 September 2004 Abstract In heterogeneous mobile ad hoc networks (MANETs), different types of mobile devices with diverse capabilities may coexist in the same network. The heterogeneity of MANETs makes end-to-end support for quality of service (QoS) guarantees more difficult than in other types of networks, not to mention the limited bandwidth and frequent topology changes of these networks. Since QoS routing is the first step toward achieving end-to-end QoS guarantees in heterogeneous MANETs, we propose a QoS routing protocol for heterogeneous MANETs. The proposed protocol, called virtual grid architecture protocol (VGAP), uses a cross-layer approach in order to provide end-to-end statistical QoS guarantees. VGAP operates on a fixed virtual rectilinear architecture (virtual grid), which is obtained using location information obtained from global positioning system (GPS). The virtual grid consists of a few, but possibly more powerful, mobile nodes known as ClusterHeads (CHs) that are elected periodically. CHs discover multiple QoS routes on the virtual grid using an extended version of the open shortest path first (OSPF) routing protocol and an extended version of WFQ scheduling policy that takes into account the wireless channel state. Moreover, VGAP utilizes a simple power control algorithm at the physical layer that provides efficient energy savings in this heterogeneous setting. Simulation experiments show that VGAP has a good performance in terms of packet delivery ratio, end-to-end packet delay, call blocking probability, and network scalability. q 2004 Elsevier B.V. All rights reserved. Keywords: Quality of service; Mobile ad hoc networks; Topological Clustering; Cross-Layer Design 1. Introduction Mobile adhoc networks (MANETs) are typically hetero- geneous networks with various types of mobile nodes. In military application, different military units ranging from soldiers to tanks can come together, hence forming an ad hoc network. In conference application, different types of mobile devices such as personal digital assistants (PDAs), smart badges, and laptops may exist in the ad hoc network at the same time. Such nodes differ in their power capacities and computational speeds. Thus, mobile nodes will have different packet generation rates, routing responsibilities, network activities, and power draining rates. Providing end-to-end support for Quality of Service (QoS) guarantees is a central and critical issue in the design of future multimedia heterogeneous MANETs. Quality of service is more difficult to guarantee in MANETs than in other types of networks for the following reasons. First, the absence of a fixed infrastructure coupled with the ability of nodes to move freely cause frequent route breakage and unpredictable topology changes. Second, the limited bandwidth resource is usually shared among adjacent nodes due to the wireless medium. Third, the nodes themselves can be heterogeneous, thus enabling an assort- ment of different types of links to be part of the same network. Numerous routing protocols were proposed to solve the routing problem in MANETs, primarily with no QoS guarantees [2,3,4,7]. A comprehensive survey on the traditional routing protocols in MANETs can be found in [1,15]. Among those protocols, position based routing protocols (PBR) [9] reduce control message overhead by utilizing location information of the nodes in the network to find the route. The location information is usually offered by 0140-3664/$ - see front matter q 2004 Elsevier B.V. All rights reserved. doi:10.1016/j.comcom.2004.07.038 Computer Communications 28 (2005) 2119–2132 www.elsevier.com/locate/comcom * Corresponding author. Tel.: C1 515 294 3580; fax: C1 515 294 8432. E-mail address: kamal@iastate.edu (A.E. Kamal).