A Survey of Routing Techniques for Mobile Collaborative Virtual Environment Applications <s> Decentralized Network Overlay <s> The combination of personal mobile devices and mobile ad-hoc networks enables the creation of mobile peer-to-peer systems in which mobile peers establish peering relationships over wireless links based on proximity. In this paper, we discuss challenges of mobile peer-to-peer middleware and present the Proem mobile peer-to-peer platform. <s> BIB001 </s> A Survey of Routing Techniques for Mobile Collaborative Virtual Environment Applications <s> Decentralized Network Overlay <s> The use of peer to peer file sharing networks such as Gnutella is proliferating on the Internet, but its use is bandwidth consuming due to the broadcast nature of some peer to peer protocols. This is undesirable for mobile devices due to their bandwidth and power constraints. This paper proposes an architecture that uses mobile agents to participate in the Gnutella network on behalf of mobile devices in order to reduce the amount of traffic for the mobile device, as well as providing support for device mobility. Using real Gnutella traffic characteristics, analysis on the viability of the architecture is presented. <s> BIB002 </s> A Survey of Routing Techniques for Mobile Collaborative Virtual Environment Applications <s> Decentralized Network Overlay <s> In recent years, the Internet has witnessed the introduction of many peer-to-peer systems designed to realize large-scale data sharing. These platforms exhibit interesting features like self-configuration, self-healing and complete decentralization, which make them appealing for employment in ad hoc environments as well. However, the impact of ad hoc dynamics on the performance of these protocols, and the different set of constraints which this emerging networking paradigm imposes, haven't been yet carefully evaluated. This paper investigates the performance of Gnutella, one of the most widely used peer-to-peer systems, when put through typical ad hoc conditions like node mobility, frequent network partitioning, etc.. We show that a straightforward implementation of the protocol is not satisfactory under the point of view of the produced overhead and the average overlay connectivity. Finally, we propose a cross-layer optimization of Gnutella, which enhances its performance up to the expectations and makes it more suitable to the degree of self-organization and self-healing required in ad hoc environments. <s> BIB003 </s> A Survey of Routing Techniques for Mobile Collaborative Virtual Environment Applications <s> Decentralized Network Overlay <s> P2P file sharing protocol and ad hoc wireless routing protocol share many intriguing similarities even though they are motivated on totally different basis. The goal of P2P file sharing system such as KaZaa is to locate a set of servers that contain a given file and disseminate it efficiently. The key problem of an ad hoc network routing protocol is to determine which route to take to reach a given remote host. P2P file sharing application on mobile ad hoc network (MANET) has gained more momentum as shown in the research of recent years. One natural way is to implement P2P application and ad hoc routing at different layers they belong to. In this paper, we argue that instead of stacking one on the top of the other, more work needs to be done to make both P2P file sharing protocol and MANET routing protocol interact with each other. We extract the commonalities of these two and design a common query/response framework on which ad hoc network routing and P2P file sharing are integrated seamlessly. The extensive experiments show that our strategy performs better than the layered approach in terms of traffic, average delay and packet delivery ratio. <s> BIB004 </s> A Survey of Routing Techniques for Mobile Collaborative Virtual Environment Applications <s> Decentralized Network Overlay <s> In recent years, Internet has witnessed the introduction of many peer-to-peer systems designed to implement large scale resource sharing. These systems exhibit interesting features like self configuration, self-healing and complete decentralization, which make the systems appealing for deployment in ad hoc environments as well. This paper enhances Gnutella with peer-node hierarchy to achieve better performance with less overhead in the ad hoc network. The proposed system introduces ultrapeer selection scheme based on the metric values and a proactive communication mechanism among ultrapeers. According to the simulation results, the proposed system gives better performance than Gnutella in terms of query success rate, query response time, and overhead. <s> BIB005 </s> A Survey of Routing Techniques for Mobile Collaborative Virtual Environment Applications <s> Decentralized Network Overlay <s> A novel caching protocol for the mobile Gnutella based network is presented and evaluated in this paper. The caching mechanism is combined with a Gnutella Ultrapeer System (GUS) to better meet the mobility requirement of collaborative virtual environments (CVEs). The contributions of this work are twofold: a) an efficient overlay formation mechanism for mobile nodes participating in a CVE; b) an optimized PONG caching technique implemented in selected nodes to control PING/PONG messages. <s> BIB006
No dedicated servers are required in a decentralized approach. A broadcast transmission is required for both, peer discovery and query requests. Gnutella [40] is taken as leader of decentralized approaches. Follows are some approaches: Choi et al BIB005 outline an enhanced Gnutella protocol for ad-hoc networks that addresses the PONG message flow problem. A peer-to-peer metric value is used to select the Ultrapeer node candidate. The proposed system provides better performance than Gnutella in terms of query hits and network overhead. In BIB005 , and BIB003 authors outline a cross layer technique to enhance the Gnutella network in mobile environment. Boukerch et al BIB006 illustrate possible solution to deploy Gnutella network over MANETs to support MCVE applications. The developed protocol is based on crosslayer approach between the application and the network layer to adopt the user interest in virtual environment. Simulation results has shown that the system provide a better performance when implemented over HSR compared to AODV, DSR and ZRP. Tang et al BIB004 propose an integrated approach for peer-topeer file sharing on multi-hop wireless networks. The approach relies on implementing FASTTRACK adopted by KaZaA over Ad Hoc On-Demand Distance Vector protocol (AODV) protocol  . Nodes use FASTTRACK routing to receive the node ID storing the requested file. Then, AODV is charged to find the best route to that node. Performance analysis shows a reduced average delay perceived by each file requester, and reduced network overhead. Seneviratne et al BIB002 addresses the problem of mobile file sharing by introducing the mobile agent. The architecture uses mobile agents to participate in Gnutella network on behalf of mobile devices, in order to reduce the volume of communications messages and the power consumption of the mobile devices. A pure peer-to-peer (i.e. without super-peers) network over MANET  was used by the PROEM BIB001 project. The proposed approach may be used for diverse mobile application like file sharing, and instant messaging. PROEM messages are based on TCP, UPD and HTTP, and it employs XML technology for their messages representation. The main limitation of the proposed approach is poor performance when the network size is increased.