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Wireless local area network (WLAN) is the one of the technologies which enable mobile users to connect to local area network through a wireless radio connection in industrial, scientific and medical (ISM) band. Since WLAN can support high data rate communications with low-cost, the use of WLAN is rapidly increasing. However, in congested region, such as shopping mall, airport, and so on, where a lot...
This paper proposes a power control MAC protocol that allows the nodes to vary transmission power. By using the minimum required transmission power, our proposed protocol can improve the spatial reuse and energy saving. The main idea is to adopt IEEE 802.11 Power Saving Mechanism (PSM) and the appropriate power control scheme for the wireless ad hoc networks. All control messages are transmitted at...
Femtocells and WiFi have been considered as viable concepts in cellular networks to increase overall system capacity. Critical functionalities for the successful integration of such technologies in macro-cellular topologies are related to radio resource allocation and interference management techniques that must ensure seamless intra-cell and inter-cell interoperation among macro- and femto users,...
While there has been extensive theoretical work on sophisticated joint resource allocation algorithms for wireless networks, their applicability to WiFi (IEEE 802.11) networks is very limited. One of the main reasons is the limitations in changing MAC parameters in current driver implementations. To this end, in this work, we developed a general cross-layer communication interface in the Linux kernel...
The rapid growths of wireless mesh infrastructure based on IEEE 802.11 has gained more and more attention from researchers on both practical and theoretical studies. Markov chain models have been widely used in describing complex systems and can be seen as a common and effective tool to analyze behaviors of 802.11 MAC protocols in distributed multiple access environments. A novel analytical model...
A new approach for wireless local area network (WLAN) installation planning is proposed in this paper. This approach is based on a multiobjective genetic algorithm and on greedy algorithms, and it is composed of two steps: network structure design and channel assignment. In the first step, the quantity, position and load balance of the access points are planned taking into account a minimum coverage...
WiFi and Zigbee sensor networks have their own usage and market but they both work in ISM frequency bands, thus causing coexistence issues. The difference of their transmission powers makes the problem even worst, as Zigbee transmission power is overruled by WiFi nodes. In this paper, we propose an interference coordination scheme based on the infrastructure operational mode. Our scheme uses the inherent...
Smartphones and portable devices are widely used these days. Data transmission networks such as 3G and Wi-Fi are used for most smartphones, and LTE is quickly increasing its market share in order to support enormous network users who cause data congestion on every part of network topology. Especially, wireless part of network suffers from starvation and congestion due to many users who wish high quality...
Crowd-sourced Wi-Fi-based localization systems utilize user input for RF scene analysis and map construction. Such systems reduce the deployment cost and privacy concerns that expert-based site survey systems can create. However, the main bottleneck of such crowd-sourcing localization systems is a bootstrapping stage, where lack of contributions by users results in no accuracy guarantee and frequent...
Multichannel communication has been proposed as alternative to adaptive (single-channel) routing protocols for mitigating the impact of interference and link dynamics in wireless sensor networks. While several studies have advocated features of both techniques (not without running up against contradicting arguments) a comprehensive study that aligns these results is still lacking. This paper aims...
Wireless Sensor Networks (WSNs) are particular networks characterized by limited energy and computational resources and, if their transmission range is limited to a person's area, they are known as Body Area Networks (BANs). When two or more BANs are co-located and operate on the same channel, active periods can overlap and transmissions can conflict. This phenomenon, that drastically reduces performances...
The extensive utilization of wireless networks requires research in the field of mitigating wireless interference to be urgent and necessary. As the standard designed for low data rate and low cost wireless personal area network, the IEEE 802.15.4 standard is widely employed to construct wireless connectivity among the inexpensive devices. However, the characteristics of low transmission power and...
In this paper we present a cooperative medium access control (MAC) protocol that is designed for a physical layer that can decode interfering transmissions in distributed wireless networks. The proposed protocol pro-actively enforces two independent packet transmissions to interfere in a controlled and cooperative manner with the help of a relay. To enable distributed, uncoordinated, and adaptive...
Exploiting the increasing ubiquitous deployment of sensor networks, the paper presents a system called WiBee that utilizes ZigBee sensors to build real-time WiFi radio maps. The design of WiBee is motivated by the observation that a ZigBee radio can sense WiFi frame transmissions although it cannot decode WiFi frames. A sensor passively listens on the wireless channel and estimates the RSS of a WiFi...
The physical layer of Wireless LAN (IEEE 802.11) supports multiple data rates and if instead of using single data rate, multiple data rates would be used then the data transmission efficiency is increased. The Rate Adaptation (RA) is such a technique adapted in Wireless LAN-802.11 to use multiple rates based on the dynamic channel condition. In this project, a new rate adaptation scheme is implemented...
External stimulation of the Tibialis anterior muscle is a technique employed to improve mobility for patients with some neurological disabilities causing drop foot. This is achieved by electrically stimulating the motor nerve which causes contraction of the muscle. For functional use the stimulation is applied during periods when the foot needs to be lifted. This period is detected using a sensor...
An adaptive channel diversity (ACD) ISA100.11-based method in wireless systems for industrial monitoring has been developed. The reliability performance (packet error rate vs. throughput) is calculated using measured data. It improves communication reliability by dynamically selecting higher quality frequency channels. Static analysis evaluation using a 30-device system with a star topology showed...
In this paper, we present a new architecture to mitigate inter-cell interference in the uplink and improve the uplink capacity of Long Term Evolution (LTE), which is named LTE-based multi-hop cellular networks with out-of-band relaying. Based on the receiving reference signal strength of User Equipments (UEs), each cell is divided into two parts, the inner circle and the outer ring. Each UE is dual-mode...
Though collisions in wireless networks can be caused either by known stations within the transmission range or by unknown hidden stations, rate adaptation algorithms that are designed to adapt to varying channel quality deal with both cases in the same manner so that they do not effectively respond to the different channel conditions. In this paper, after examining the core issues regarding rate adaptation,...
Achieving fair and optimal data rates in wireless networks is an area of continued research. Distributed algorithms have been developed directly from mathematical optimization problems that guarantee fair and optimal rates. However, the algorithms developed thus far are based on simplified models of wireless networks. This research presents a first-principles model of wireless networks that reduces...
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