Multi-hop Wireless Local Area Networks Research Articles

Towards Enabling Multihop Wireless Local Area Networks for Disaster Communications

xCalamities such as earthquakes and tsunami affect communication services by devastating the communication network and electrical infrastructure. Multihop relay networks can be deployed to restore the communication environment quickly in catastrophe-stricken areas. However, performance in terms of throughput is affected by deploying the relay networks. In wireless local area networks (WLANs), the primary purpose of multiband transmission employing multihop relay networks is to increase the throughput and reduce the latency. In the future, wireless networks are believed to carry high throughput, more data rates, and less latency by expanding bandwidth-demanding applications. Simultaneous multiband transmission in WLAN systems is considered to increase the coverage area without power escalation. Due to the inherent characteristics of different bands and channel conditions, transmission rates tend to be different. The impact of such conditions may cater to the disproportional distribution of data among bands, causing some of the bands to be overwhelmed, which incurs buffer overflow and packet loss. In contrast, the channel capacity of some of the bands remains underutilized. In this paper, we consider the channel conditions and transmission rates of each band on either side of the relay to address the problems mentioned above. Furthermore, this paper proposes a load distribution-based end-to-end traffic scheduling technique to improve system performance. The simulation results demonstrate the effectiveness of our proposed method with maximizing throughput and minimizing end-to-end delay.

Combine and Conquer: Simultaneous Transmission Over Multiband Multi-Hop WLAN Systems

Multi-hop relay networks are deployed to restore communication environment in the catastrophe stricken area. Deployment of these networks are fast and easy but performance is low due to the relay nature of the networks. Given the surge of bandwidth hungry application, performance such as high data rates, high throughput and ultra-low latency is a concern in traditional one-hop Wireless Local Area Networks (WLANs) as well. Simultaneous transmission over multiple bands is a compendious solution that has the potential to significantly boost data rates and flexibility. It will enhance the network utilization and performance of high-bandwidth applications effectively and efficiently. However, there are certain challenges that need to be addressed before taking full advantage of simultaneous transmission over multiple bands. In this work, we outline the factors affecting the performance such as throughput and end-to-end delay in multiband multi-hop WLANs. Considering these factors, we design an end-to-end traffic scheduling technique that minimizes end-to-end delay and maximizes throughput. We design a mixed integer linear program (MILP) that optimizes end-to-end delay and maximizes throughput. Illustrative numerical results show that proposed technique effectively minimizes end-to-end delay and maximizes throughput.

An Efficient Performance analysis of IEEE 802.11 in Multi-Hop Wireless Local Area Network

An Efficient Performance analysis of IEEE 802.11 in Multi-Hop Wireless Local Area Network

Seamless internet 3G and opportunistic WLAN vehicular connectivity

Most of the cellular network operators are nowadays striving to solve the problem caused by the increasing demand of mobile data users. In the near future, vehicles will be equipped not only with cellular connectivity, but also with dedicated short-range wireless devices, used to connect via single or multiple hops to fixed road side units attached to the infrastructure network to gain Internet access. Taking this hybrid-connectivity scenario, we propose S eamless I nternet 3G and Opportunistic WL AN V ehicular I nternet Co nnectivity (SILVIO), a solution for providing Internet connectivity in multi-hop vehicular ad hoc networks. Vehicles use the cellular network to assure always-on connectivity, while they opportunistically select to offload some non-critical flows to the multi-hop wireless local area network (WLAN). The advantages of this approach are twofold: the users can benefit from a higher bandwidth, while the operators can alleviate their overloaded cellular networks. SILVIO makes use of existing standard mobility mechanisms integrated, enhanced and extended to provide a seamless connectivity experience without introducing much complexity nor signalling overhead. One of the main contributions of this article is the proposal and analysis of different handover strategies between 3G and multi-hop WLAN networks for the vehicular scenario. A trace-driven simulator was developed to evaluate the performance improvements provided by SILVIO. Real traffic traces from the city of Madrid were used to feed the simulator which considers large vehicles as obstacles, as well. The obtained results show that using SILVIO the cellular network can be offloaded by a factor up to 80%.

Power-Efficient Spatial Reusable Channel Assignment Scheme in WLAN Mesh Networks

Interference has strong effect on the available bandwidth of wireless local area network (WLAN) based mesh networks. The channel assignment problem for multi-radio multi-channel multihop WLAN mesh ...

Performance evaluation of video streaming over multi-hop wireless local area networks

IEEE 802.11 WLAN is preferred for IPTV in-home distribution, but the achievable throughput and coverage are still limited due to the high attenuation and interference in a household environment. Through our measurement study with a WDS-based multi-hop wireless testbed, we have found that it is possible for multi-hop wireless networks to increase the coverage and improve the video streaming performance at the same time. To analyze the throughput of IEEE 802.11 multihop wireless networks, we propose an extended two-dimensional Markov-chain model in this paper. Different from existing work, our model takes the retry limit and post-backoff stage into account to better capture the behavior of IEEE 802.11 MAC protocols in a non-ideal channel and with non-persistent traffic. The throughput analysis is validated by network simulation with extended lower and upper-layer simulation modules. The achievable throughput gives an upper bound of the video streaming performance, which is further validated by our H.264-based video streaming simulation with application-layer performance metrics. The results correspond to the observation we had on the multi-hop testbed. Further, this paper also provides some guidance on how to achieve the optimal balance for a given scenario, which is important when deploying video streaming services with end-to-end quality-of-service provisioning.

An admission control algorithm for multi-hop 802.11e-based WLANs

Recently, wireless local area network (WLAN) hotspots have been deployed in many areas. The new IEEE 802.11e standard further provides quality of service (QoS) provisioning by grouping the applications into four different access categories. The coverage area of WLANs can be extended by allowing the neighboring mobile devices to relay data to the access points. This concept is known as multi-hop WLANs or wireless mesh networks. Due to the limited network capacity and the contention-based channel access mechanism, admission control is required to regulate the number of simultaneous flows to maintain QoS. The multi-hop extension of WLANs present further challenges for admission control design due to the location-dependent contention in the network. In this paper, we propose an admission control algorithm for multi-hop 802.11e-based WLANs. In our proposed admission control algorithm, we first use a contention graph to model the contention situation in the multi-hop WLAN. It is followed by an estimation of the capacity for each maximal clique in the contention graph. A new flow is admitted if the aggregated traffic load is less than the estimated network capacity. The proposed algorithm supports both stationary and mobile nodes, as well as handoff and new connections. Simulation results show that the proposed algorithm is effective in providing QoS guarantee to the existing voice and video flows while maintaining a good performance for best effort traffic.

A symbotic perspective on low-cost cellular and multihop WLAN interworking solutions

Interworking between wireless local area networks (WLANs) and cellular networks (such as 2G and 3G) is expected to break new ground for sophisticated business models. Omnipresent cellular networks have a well-defined infrastructure, but lack capability to provide broadband and/or real-time services (e.g., streaming video and gaming). Conversely, WLANs supports high data rates, while the infrastructure for service provision is vague. Therefore, the combination of the cellular core network infrastructure with its service centers and accounting capabilities with the achievable data rate of WLANs can provide the possibility of offering new services to the customer. This interworking is being considered in different standardization and operational activities. WLAN hotspots are already on the way, but the high installation costs of WLANs, especially for larger hotspots, are repressing a faster evolution. The installation costs are mainly driven by the cabling infrastructure. To reduce these costs and to gain flexibility, we advocate exploiting multihop capability for WLAN coverage extension by introducing the concept of virtual access points. However, the high data rates of WLAN solutions are hindered by the standard IEEE 802.11 MAC protocol, which has been shown to be inappropriate for multihop operation. In this article we consider an improved version of the IEEE 802.11 MAC that involves only minor changes to the existing standard, which allows for a faster deployment and the usability of the approach in existing interworking scenarios. The specific contribution of this article is a thorough exploration, by means of simulation, of the performance of such an approach. In particular, we demonstrate that the enhanced MAC is capable of offering high data rates in multihop WLAN extensions to the cellular network. Besides the networking structure, a pertinent issue in the WLAN cellular symbiosis is security. In this respect we discuss multihop operation in light of current interworking (security) activities.