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Very often a denser deployment of APs is required to increase the coverage and capacity in IEEE 802.11 WLAN. It increases the number of APs with overlapping coverage areas. Such overlapping eventually makes more and more clients to fall in the common coverage area of several APs. Interfering APs require different frequency channels for operation in order to avoid the co-channel interference between...
Multi-User Coordinated Multi-Point (MU-CoMP) transmission mode is considered as one of the key technologies which offer a good quality of service to low capacity users while maintaining a high spectral efficiency in the system. However, MU-CoMP networks have to determine the total number of users supported by CoMP operation as well as the size of the SDMA (Spatial Division Multiple Access) users'...
Researches on scheduling in cognitive radio (CR) networks (CRN) mostly focus on spectrum efficiency before. With more portable devices supplied by energy-limited batteries applying CR technology, it needs to design a new scheduling strategy to improve energy efficiency. In this paper, considering frequency switching delay, adaptive power and minimum rate requirements, we formulate the scheduling problem...
One of the main purpose for heterogeneous networks (HetNet) is to reduce the power consumption for various spectrum allocation schemes. Large-scale user behavior in a two-tier HetNet is considered for the energy-efficient spectrum allocation, which characterizes the macro BSs that guarantee traffic requirements in non-hotspot regions and micro BSs that guarantee traffic requirements in hotspot regions...
In this paper we propose a utility-based scheduling mechanism for mixed traffic in wireless networks to mitigate the problem that current scheduling algorithms cannot have a good performance in mixed traffic. The proposed algorithm called UBSA (Utility-Based Scheduling Algorithm) works in wired-wireless hybrid networks. Packets of diverse QoS (Quality of Service) classes are allocated to different...
Channel allocation and Channel access are considered to be the most important issues in Wireless Communication System. MAC protocols for wireless sensor networks based on CSMA/CA induce high overhead due to RTS/CTS packets and does not completely eliminate hidden terminal problems. A new technique, called Grid based Channel allocation and Access scheduling using Latin Squares (GAALS) can be effectively...
In multi-channel wireless networks, the interferences due to simultaneous transmissions of neighboring nodes can be reduced by assigning different non-overlapping orthogonal channels to sender-receiver pairs that may interfere with each other. However, if the number of non-overlapping channels is smaller than that of interfering nodes, we cannot avoid assigning the same channels to adjacent interfering...
An overlaid mesh with unequal RF nodes placement has been introduced to improve network performance of wireless network-on-chip benefited from the greatly reduced network diameter. Traffic however can easily get crowded at big RF nodes due to the sharing and competition of multi-channel usage. To alleviate traffic congestion, a load adaptive channel distribution and arbitration scheme is proposed...
The performance of multi-channel (MRMC) wireless mesh networks (WMNs) is largely affected by interference, which depends on router placement, traffic routing and channel assignment. This work seeks to jointly optimize the placement, routing and channel assignment for mesh deployment given flow requirements. The problem is complex because router placement changes network topology which in turns impacts...
IEEE 802.22 standard is the first worldwide standard using cognitive radio (CR) technology for wireless regional area networks (WRANs). Orthogonal frequency-division multiple access (OFDMA) is employed for point-to-multi-point (P2M) communication between base stations (BS) and customer premises equipments (CPEs) in WRANs. The large coverage of a single cell (up to 100 km of radius) is the unique feature...
One of the crucial challenges experienced by Wireless Sensor Networks (WSNs) is the increasing number of devices sharing the limited spectrum of the ISM band. As a result, a new concept of Cognitive Wireless Sensor Networks (CWSNs) has been proposed in order to achieve reliable and efficient communication via spectrum awareness and intelligent adaption. Based on such concept, this paper proposes novel...
The increased density of wireless local area network (wireless LAN) access points (APs) based on the IEEE 802.11 standard has induced inter-cell interference that severely degrades system performance. In order to mitigate this issue, this paper proposes an efficient network-controlled channel allocation scheme that can be applied to a managed wireless LAN system with a central coordinator. On the...
Since communications services become much more demanded after disaster strikes, it is necessary to promptly set up a temporary communications infrastructure to provide services to those in need. The Movable and Deployable Resource Unit (MDRU) based Wireless Mesh Network (WMN) is an attractive candidate to achieving this goal. In MDRU based WMN, the MDRU is transported to the disaster affected area...
Flexible channelization can enhance spectrum efficiency by adapting channel bandwidth and center frequency compared with traditional fixed width channel. The key challenge of this new mechanism lies in how to determine proper channel width for each link in a distributed manner without coordination. In this work, we investigate the spectrum sharing problem with flexible channelization from game-theoretic...
The goal of IEEE 802.11ac is to provide very high throughput~(VHT) performance while at the same time guaranteeing backward compatibility. For the goal, 802.11ac adopts the channel bonding technique that makes use of multiple 20MHz channels in 5GHz band. Due to the heterogeneity of bandwidth that each device exploits, and the fixed total transmission power, a problem called `Hidden Channel' arises...
Wireless mesh network (WMN), radio nodes that form a mesh topology, is an interesting architectural candidate for the future wireless Internet. A dense access network can rapidly be deployed at a reasonable cost because there is no need to wire the mesh access points. However, WMNs typically do not perform well with latency-sensitive data traffic, such as Voice over IP (VoIP), due to restricted bandwidth...
Maintaining fairness in Wireless Mesh Networks (WMNs) is quite important but has been given less attention relative to other aspects such as capacity maximization and maintaining connectivity. IEEE 802.11 MAC protocol has been used as the standard for WMNs although it has been initially designed to operate in wireless local area networks. It is known to be unfair in multi-hop networks. This unfairness...
Recent studies show that the Dedicated Short Range Communication (DSRC) band allocated to vehicular networks is insufficient to carry the wireless traffic load generated by emerging applications for vehicular systems. A promising bandwidth expansion possibility presents itself through the release of large TV band spectra by FCC for cognitive access. One of the primary challenges of the so-called TV...
Wireless mesh network is an emerging technology for the next generation wireless Internet. It works as a backhaul for other wireless network. There are number of issues which need to be considering in wireless mesh network. As in other networks like MANET, ADHOC, SENSOR power is the major constrained. But it is not so in WMN. So, Power can be optimally utilised. It can be used to increase throughput...
It is emerging to deploy multihop cellular networks (MCNs) for increasing cell capacity and to provide large coverage to mobile users without increasing infrastructure cost. It very much decreases the dead-spot and hot-spot problems with rapidly growing mobile users in cellular networks. However, channel assignment is the most important concern in these networks. Quite a few recent proposals has been...
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