Joint Access Point Placement and Channel Assignment for 802.11 Wireless Local Area Networks

To deploy a multi-cell IEEE 802.11 wireless local area network (WLAN), access point (AP) placement and channel assignment are two primary design issues. For a given pattern of traffic demands, we aim at maximizing not only the overall system throughput, but also the fairness in resource sharing among mobile terminals. A novel method for estimating the system throughput of a multi-cell WLAN is proposed. An important feature of this method is that cochannel overlapping is allowed. Unlike conventional approaches that decouple AP placement and channel assignment into two phases, we propose to solve the two problems jointly for better performance. Due to the high computational complexity involved in exhaustive searching, an efficient local searching algorithm, called patching algorithm, is also designed. Numerical results show that for a typical indoor environment, the patching algorithm can provide a close-to-optimal performance with much lower time complexity.published_or_final_versio

Jointly Optimizing Placement and Inference for Beacon-based Localization

The ability of robots to estimate their location is crucial for a wide variety of autonomous operations. In settings where GPS is unavailable, measurements of transmissions from fixed beacons provide an effective means of estimating a robot's location as it navigates. The accuracy of such a beacon-based localization system depends both on how beacons are distributed in the environment, and how the robot's location is inferred based on noisy and potentially ambiguous measurements. We propose an approach for making these design decisions automatically and without expert supervision, by explicitly searching for the placement and inference strategies that, together, are optimal for a given environment. Since this search is computationally expensive, our approach encodes beacon placement as a differential neural layer that interfaces with a neural network for inference. This formulation allows us to employ standard techniques for training neural networks to carry out the joint optimization. We evaluate this approach on a variety of environments and settings, and find that it is able to discover designs that enable high localization accuracy.Comment: Appeared at 2017 International Conference on Intelligent Robots and Systems (IROS

Improving the Performance of Wireless LANs

This book quantifies the key factors of WLAN performance and describes methods for improvement. It provides theoretical background and empirical results for the optimum planning and deployment of indoor WLAN systems, explaining the fundamentals while supplying guidelines for design, modeling, and performance evaluation. It discusses environmental effects on WLAN systems, protocol redesign for routing and MAC, and traffic distribution; examines emerging and future network technologies; and includes radio propagation and site measurements, simulations for various network design scenarios, numerous illustrations, practical examples, and learning aids

Optimal Access Point Selection and Channel Assignment in IEEE 802.11 Networks

Designing 802.11 wireless networks includes two major components: selection of access points (APs) in the demand areas and assignment of radio frequencies to each AP. Coverage and capacity are some key issues when placing APs in a demand area. APs need to cover all users. A user is considered covered if the power received from its corresponding AP is greater than a given threshold. Moreover, from a capacity standpoint, APs need to provide certain minimum bandwidth to users located in the coverage area. A major challenge in designing wireless networks is the frequency assignment problem. The 802.11 wireless LANs operate in the unlicensed ISM frequency, and all APs share the same frequency. As a result, as 802.11 APs become widely deployed, they start to interfere with each other and degrade network throughput. In consequence, efficient assignment of channels becomes necessary to avoid and minimize interference. In this work, an optimal AP selection was developed by balancing traffic load. An optimization problem was formulated that minimizes heavy congestion. As a result, APs in wireless LANs will have well distributed traffic loads, which maximize the throughput of the network. The channel assignment algorithm was designed by minimizing channel interference between APs. The optimization algorithm assigns channels in such a way that minimizes co-channel and adjacent channel interference resulting in higher throughput

DYNAMIC ROUTING WITH CROSS-LAYER ADAPTATIONS FOR MULTI-HOP WIRELESS NETWORKS

In recent years there has been a proliferation of research on a number of wireless multi-hop networks that include mobile ad-hoc networks, wireless mesh networks, and wireless sensor networks (WSNs). Routing protocols in such networks are of- ten required to meet design objectives that include a combination of factors such as throughput, delay, energy consumption, network lifetime etc. In addition, many mod- ern wireless networks are equipped with multi-channel radios, where channel selection plays an important role in achieving the same design objectives. Consequently, ad- dressing the routing problem together with cross-layer adaptations such as channel selection is an important issue in such networks. In this work, we study the joint routing and channel selection problem that spans two domains of wireless networks. The first is a cost-effective and scalable wireless-optical access networks which is a combination of high-capacity optical access and unethered wireless access. The joint routing and channel selection problem in this case is addressed under an anycasting paradigm. In addition, we address two other problems in the context of wireless- optical access networks. The first is on optimal gateway placement and network planning for serving a given set of users. And the second is the development of an analytical model to evaluate the performance of the IEEE 802.11 DCF in radio-over- fiber wireless LANs. The second domain involves resource constrained WSNs where we focus on route and channel selection for network lifetime maximization. Here, the problem is further exacerbated by distributed power control, that introduces addi- tional design considerations. Both problems involve cross-layer adaptations that must be solved together with routing. Finally, we present an analytical model for lifetime calculation in multi-channel, asynchronous WSNs under optimal power control

A Minimum-Spanning-Tree-Inspired Algorithm for Channel Assignment in 802.11 Networks

Channel assignment in 2.4 GHz band of 802.11 standard is still important issue as a lot of 2.4 GHz devices are in use. This band  offers only three non-overlapping channels, so in crowded environment users can suffer from high interference level.  In this paper, a greedy algorithm inspired by the Prim’s algorithm for finding minimum spanning trees (MSTs) in undirected graphs is considered for channel assignment in this type of networks. The proposed solution tested for example network distributions achieves results close to the exhaustive approach and is, in many cases, several orders of magnitude faster

On the long-term wireless network deployment strategies

Master'sMASTER OF ENGINEERIN

Planning and realization of a WiFi 6 network to replace wired connections in an enterprise environment

WiFi (Wireless Fidelity) is a popular wireless LAN technology. It provides broadband wireless connectivity to all the users in the unlicensed 2.4 GHz and 5 GHz frequency bands. Given the fact that the WiFi technology is much easier and cost-efficient to deploy, it is rapidly gaining acceptance as an alternative to a wired local area network. Nowadays the Wireless access to data is a necessity for everyone in the daily life. Considering the last 30 years, the unlimited access to information has transformed entire industries, fueling growth, productivity and profits.The WiFi technology, which is governed by the IEEE 802.11 standards body, has played a key role in this transformation. In fact, thanks to WiFi, users can benefit of low cost access to high data rate wireless connectivity. The first version of the IEEE 802.11 protocol was released in 1997. IEEE 802.11 has been improved with different versions in order to enhance the throughput and support new technologies. WiFi networks are now experiencing the bandwidth-demanding media content as well as multiple WiFi devices for each user. As a consequence of this, WiFi 6, which is based on the IEEE 802.11ax standard, is focused on improving the efficiency of the radio link. However, there is a relatively modest increase in peak data rate too. In this thesis we have planned and realized a WiFi 6 network to replace wired connections in an enterprise environment. To do this the optimal access point placement problem has been taken into account, resulting in an improvement of the coverage. Subsequently, after the configuration from the controller, the performance of the new network has been tested in order to study if WiFi 6 can be used instead of wired connections.WiFi (Wireless Fidelity) is a popular wireless LAN technology. It provides broadband wireless connectivity to all the users in the unlicensed 2.4 GHz and 5 GHz frequency bands. Given the fact that the WiFi technology is much easier and cost-efficient to deploy, it is rapidly gaining acceptance as an alternative to a wired local area network. Nowadays the Wireless access to data is a necessity for everyone in the daily life. Considering the last 30 years, the unlimited access to information has transformed entire industries, fueling growth, productivity and profits.The WiFi technology, which is governed by the IEEE 802.11 standards body, has played a key role in this transformation. In fact, thanks to WiFi, users can benefit of low cost access to high data rate wireless connectivity. The first version of the IEEE 802.11 protocol was released in 1997. IEEE 802.11 has been improved with different versions in order to enhance the throughput and support new technologies. WiFi networks are now experiencing the bandwidth-demanding media content as well as multiple WiFi devices for each user. As a consequence of this, WiFi 6, which is based on the IEEE 802.11ax standard, is focused on improving the efficiency of the radio link. However, there is a relatively modest increase in peak data rate too. In this thesis we have planned and realized a WiFi 6 network to replace wired connections in an enterprise environment. To do this the optimal access point placement problem has been taken into account, resulting in an improvement of the coverage. Subsequently, after the configuration from the controller, the performance of the new network has been tested in order to study if WiFi 6 can be used instead of wired connections