Integrated cellular and ad hoc relaying systems (iCAR) is a new wireless system architecture based on the integration of cellular and modern ad hoc relaying technologies. It addresses the congestion problem due to unbalanced traffic in a cellular system and provides interoperability for heterogeneous networks. The iCAR system can efficiently balance traffic loads between cells by using ad hoc relaying stations (ARS) to relay traffic from one cell to another dynamically. This not only increases the system's capacity cost effectively, but also reduces transmission power for mobile hosts and extends system coverage. In this paper, we compare the performance of the iCAR system with conventional cellular systems in terms of the call blocking/dropping probability, throughput, and signaling overhead via analysis and simulation. Our results show that with a limited number of ARSs and some increase in the signaling overhead (as well as hardware complexity), the call blocking/dropping probability in a congested cell and the overall system can be reduced.

Few real-world applications of mobile ad hoc networks have been developed or deployed outside the military environment, and no traces of actual node movement in a real ad hoc network have been available. In this paper, we propose a novel commercial application of ad hoc networking, we describe and evaluate a multitier ad hoc network architecture and routing protocol for this system, and we document a new source of real mobility traces to support detailed simulation of ad hoc network applications on a large scale. The proposed system, which we call Ad Hoc City,isa multitier wireless ad hoc network routing architecture for generalpurpose wide-area communication. The backbone network in this architecture is itself also a mobile multihop network, composed of wireless devices mounted on mobile fleets such as city buses or delivery vehicles. We evaluate our proposed design through simulation based on traces of the actual movement of the fleet of city buses in the Seattle, Washington metropolitan area, on their normal routes providing passenger bus service throughout the city. 1.

While several approaches have been proposed in literature for improving the performance of wireless packet data networks, a recent class of approaches has focused on improving the underlying wireless network model itself. Several of such approaches have shown that using peer-to-peer communication, a mode of communication used typically in ad-hoc wireless networks, can result in performance improvement in terms of both throughput and energy consumption. However, the true impact of using the ad-hoc network model in wireless packet data networks has neither been comprehensively studied, nor characterized. In this paper, we investigate the benefits of using an ad-hoc network model in cellular wireless packet data networks. We find that while the ad-hoc network model has significantly better spatial reuse characteristics, the improved spatial reuse does not translate into better throughput performance. Furthermore, although considerable improvement is seen in energy consumption performance, we observe that using the ad-hoc network model as-is might actually degrade the throughput performance of the network. We identify and discuss the reasons behind these observations. Finally, using the insights gained through our performance evaluations, we discuss strawman versions of three techniques which when used in tandem with the ad-hoc network model result in better throughput, energy consumption, fairness, and mobility-resilience characteristics. Through our simulation results, we motivate that using the ad-hoc network model in conventional wireless packet data networks is a promising approach when the network model is complemented with appropriate mechanisms. 1.

Correlated usage of mobile devices intensifies traffic burstness and poses threat of congestion to current cellular-based wireless infrastructures. Inspired by the idea of integrating a cellular-based infrastructure with ad-hoc relaying, we propose a new architecture for the next-generation wireless networks, termed PARCelS, which utilizes roaming mobile hosts to perform route relaying. PARCelS is cost-effective as it saves the large investment in existent cellular-based infrastructures and does not need dedicated mobile devices. Our evaluations show that PARCelS can balance traffic load, avoid traffic congestion, and reduce latency.

iCAR is a new wireless system architecture based on the integration of cellular and modern ad hoc relaying technologies. It addresses the congestion problem due to limited channel access in a cellular system and provides interoperability for heterogeneous networks. The iCAR system can efficiently balance traffic loads and share channel resource between cells by using ad hoc relaying stations (ARS) to relay traffic from one cell to another dynamically. Analyzing the performance of iCAR is nontrivial as the classic Erlang-B formula no longer applies when relaying is used. In this paper, we build multi-dimensional Markov chains to analyze the performance of the iCAR system in terms of the call blocking probability. In particular, we develop an approximate model as well as an accurate model. While it can be time-consuming and tedious to obtain the solutions of the accurate model, the approximate model yields analytical results that are close to the simulation results we obtained previously. Our results show that with a limited number of ARSs, the call blocking probability in a congested cell as well as the overall system can be reduced.

In distributed wireless networks, where nodes actively participate in helping communication for other nodes, they are typically unaware of their neighourhood and hence have to “estimate ” it before sending any useful data. In this paper, we formalize the concept of node neighbourhood by introducing the notion of network channel, in which all nodes become part of a large channel. The notion of network channel is then used to study routing in decode and forward networks. To do the same, we introduce the concept of network coherence time, which denotes the time for which the network topology remains approximately constant. The new concepts are used to study the tradeoffs between encoding rate of route discovery packets, number of discovered routes and accuracy of subsequent network channel estimation. Finally, we propose a simple adaptive algorithm for route selection using outage capacity as the metric for route selection, and show that our algorithm outperforms the existing route selection based on the minimum hop count.

One of the major challenges that wireless system carriers and infrastructure providers will face is to meet the increased bandwidth demand of mobile Internet users, and deal with the bursty and unbalanced IP traffic, which exacerbate the problem of limited capacity in cellular systems. The iCAR (integrated Cellular and Ad hoc Relaying) system was recently proposed to address the congestion problem due to the limited bandwidth in a cellular system and provide interoperability for heterogeneous networks. In this paper, we present the distributed signaling and routing protocols for establishing QoS (i.e. bandwidth) guaranteed connections for IP traffic in iCAR. In particular, we discuss how a relaying route between a MH (Mobile Host) and a BTS (Base Transceiver Station) in a nearby cell can be established via ARS's (Ad hoc Relaying Stations), and evaluate the performance of the protocols in terms of request rejection rate and signaling overhead through simulations.

In this paper, we propose the Ad-hoc CEllular NETwork (ACENET), a heterogeneous wireless network architecture for 3.5 - generation (3.5G) and fourth-generation (4G) mobile systems. We propose an IP-based integrated wireless routing scheme for the integration of heterogeneous wireless networking technologies in 3.5G and 4G ACENET. We also propose an integrated wireless MAC scheme for 4G ACENET. ACENET integrates cellular networks, wireless LANs, and ad hoc networks and enables heterogeneous wireless devices and technologies such as CDMA,IEEE 802.11, Bluetooth, and/or HiperLAN/2 to coexist and assist each other for communications with higher throughput, lower power, better quality-ofservice (QoS), versatility, and low cost.

In this abstract, we report a new wireless network archi-tecture, called the dynamic cellular network (DCN), that we are currently developing for achieving high throughput and low power consumption in mobile communications. Quality of service (QoS) can be guaranteed in DCNs even when an active mobile station moves into a cell that has been 100% utilized. In addition to supporting all the applications avail-able in conventional cellular networks, DCNs may enable many other potential applications that are otherwise impos-sible. 1.

The allocation of IP addresses in hybrid wireless networks is one of the most critical issues in all-IP converged wireless networks. The reason is that centralized IP address allocation mechanisms may not be available in networks comprised of heterogeneous mobile wireless devices. In this paper, we propose Zero-Maintenance Address Allocation (ZAL), a fully distributed address allocation algorithm with extremely low communication overhead. ZAL outperforms existing solutions in many important aspects, and eliminates permanent duplication of IP addresses. ZAL is completely free from periodical maintenance messages, timeouts, delays, and modification of existing network protocols. Theoretically, we prove that ZAL suffers negligible probability of temporary address duplication, while minimizing the usage of address space. In our experiments, we can successfully allocate addresses to a network of 480 nodes with no duplication of IP addresses when the size of available address space is 1024 (2 ) or larger. Even for an available address space of size 512, in average, temporary address duplication can be resolved within 60 seconds after the node joins the network.