Aeronautical Ad Hoc Networks Ehssan Sakhaee † , Abbas Jamalipour † , and Nei Kato ‡ † School of Electrical & Information Engineering, University of Sydney, Australia ‡ Graduate School of Information Sciences, Tohoku University, Japan Abstract—There has been an enormous growth in Mobile Ad hoc NETworks (MANETs) in land based small to medium size networks with relatively strict power and resources. In this paper the concept of ad hoc networking between aircraft is introduced, which can be considered as a novel approach in increasing the data rate and practicality of future in-flight broadband Internet access. This method also reduces the Internet traffic load on satellite nodes and also propagation delay for real-time traffic transmissions, by effectively bypassing the satellite link for non- real time data. A dynamic routing algorithm is also proposed for efficient routing in this kind of system. A new cost metric for increasing path duration is introduced to assist routing in the proposed ad hoc network. I. INTRODUCTION The wide spread use of on-board broadband Internet access particularly in the case of aeronautical systems is gradually taking off. Already in 2005, Connexion by Boeing [1] has implemented broadband Internet on long-haul flights including Lufthansa, Japan Airlines, Scandinavian Airlines, and many others have signed definite agreements to implement this service on their commercial aircrafts. Although broadband speeds are offered, it is shared among users, and as the deployment of these services continues and more and more users begin exploiting these services, the need for an efficient system model and its management would become an integral part of the system. Furthermore, it is desired to find an alternative approach to bypass the long propagation delay of the satellite link for delay sensitive Internet applications. There have been recent studies in aeronautical satellite communication, where the communication is limited to satellite [2-4]. In [5], the idea of direct communication to ground for Internet access was envisaged. The proposed extension to the initial model in [5] is to provide direct communications, also among planes. This increases the methods of wireless data communication as shown in Fig. 1. This can be seen as a three-layered topology as shown in Fig. 2, where the top layer is the satellite layer, the middle layer is the aircraft layer, and the bottom layer is the ground station (Earth segment) layer. These layers could effectively interact with each other using inter-layer links. In this paper the focus will be on the middle layer, where airplanes directly communicate with each other. Due to the high mobility of planes, the network topology of airplane nodes falls into the Mobile Ad hoc NETwork (MANET) category. Hence the ad hoc networking among planes will be the focus of this paper. The vast interest in MANETs in the past couple of years has extended the vision of how infrastructure-less mobile nodes can communicate with one another. The primary application of ad-hoc networks has been for small to medium scale devices that are usually restricted by power, bandwidth, and range. Examples of these are the Bluetooth devices and IEEE 802.11 Wireless LAN [6]. However MANETs should not be limited to small devices and localized parameters. It may be possible to extend a MANET to almost a global network level where the mobile entities are large-scale systems having relatively large resources and transmission power. This is especially true when considering cars or commercial aeronautical systems. Additionally, when considering ad hoc networking in the aeronautical system (or any mobile system for that matter), mobility behaviors should be taken into account so that durable links are identified and established between nodes in order for the successful transmission and reception of data. Different mobile devices Internet Gateway Aircraft Satellite Intra-Layer Links Inter-Layer Links Figure 2. Layered topology of routing in aeronautical systems. Figure 1. Methods of aeronautical data communications. This full text paper was peer reviewed at the direction of IEEE Communications Society subject matter experts for publication in the WCNC 2006 proceedings. 1-4244-0270-0/06/$20.00 (c)2006 IEEE