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Dissemination latency is critical to the applications of {\em cognitive radio networks}, which have become an important component of current communication infrastructure. This paper investigates the distribution of dissemination latency in a cognitive radio network where licensed users (primary users) are static and cognitive radio users (secondary users) are moving under general mobility, which provides...
Applicability of the concept of Flow-Aware Networking (FAN) for QoS assurance in wireless networks is studied in the paper. The link utilization efficiency for six versions of the TCP protocol in the FAN environment is investigated and compared. The second contribution of the paper is a new congestion control mechanism for FAN, referred to as RAMAF (Remove and Accept Most Active Flows), that fulfills...
Network throughput of the best-effort networks as typified by the Internet and wireless networks is often insufficient for multimedia communication, and it spoils the quality of communication. Therefore, it is important to analyze a dynamic characteristics of the throughput when multimedia traffic is injected. We point out that the dynamics of the throughput has the viscosity and the elasticity because...
This paper proposes a location-based MAC (LMAC) scheme for wireless networks with randomly placed nodes. This scheme regulates channel access by sharing local location information among transmitters. A lattice approximation approach is used to derive upper and lower bound for the success probability for a typical transmission attempt. Numerical results show that with the node density and link distance...
Congestion control for wireless networks is much more challenging than that for wired networks, due to the limited wireless spectrum and severe impairments of wireless medium which suffer time-varying fading, shadowing, interference, etc. Although the stability of the Internet using TCP congestion control and active queue management (AQM) schemes has been extensively investigated, effective congestion...
In wireless networks a packet can be lost due to numerous reasons, such as congestion, medium related errors, routing and mobility. In these scenarios, the real congestion status of the network is crucial to develop accurate and efficient congestion control protocols. Some of the most known and recent protocols developed to provide faster and lighter congestion control are the eXplicit Control Protocol...
Multi-Packet Reception (MPR) enables simultaneous receptions from different transmitters to a single receiver, which has been demonstrated to bring capacity improvement in wireless network. However, MPR does not improve the transmission capability of intermediate relay nodes in a multi-hop routing and thus these nodes may become the bottlenecks for increasing throughput despite of great reception...
IPTV multicasting is an important service for residential users. In this paper, we explore how to allocate resources to different layer-encoded IPTV programs using multicast services in relay-assisted centralized wireless access networks. We consider the scenario of two-hop relay stations, and the MAC protocol is OFDMA-based, as in IEEE 802.16m or Long Term Evolution-Advanced (LTE-A). We formulate...
This paper proposes a dynamic primal-dual type scheduling algorithm in wireless networks, which achieves optimal throughput even with uncertain parameters. In wireless networks, such uncertain parameters are generated by complicated stochastic dynamics, such as random packet arrivals, channel fading, and node mobilities. The algorithm is a generalization of the well-known max-weight scheduling algorithm...
Wireless links are often unreliable and prone to transmission error due to varying channel conditions. These can degrade the performance in wireless networks, particularly for applications with tight quality-of-service requirements. A common remedy is to use channel coding where the transmitter node adds redundant bits to the transmitted packets in order to reduce the error probability at the receiver...
Cognitive Radio (CR) networks are emerging as a viable candidate to resolve the conflict between increasing demand for spectrum and spectrum shortage. The essential purpose of a CR network is to improve the network spectrum efficiency, which, however, may not be achieved if a CR network is inappropriately configured. In decentralized overlaid networks, the throughput of the primary network will decrease...
In this paper we study the connection availability of wireless networks from the perspective of end users with individual mobility, in contrast to existing studies mainly focusing on network-centric connectivity. Specifically, we evaluate the user connectivity by two metrics: neighbor connection time and neighbor isolation time. The former is the time for a node being connected with at least one neighbor;...
In this paper, we develop a cross-layer algorithm to minimize energy consumption in multi-hop wireless networks with finite buffers. Our algorithm guarantees a flow-based minimum data rate and a deterministic buffer size upper-bound for individual flows at network nodes. The algorithm jointly integrates congestion control, power allocation, routing and link rate scheduling. In addition, the algorithm...
Network-coded cooperative communications (NC-CC) refers to the use of network coding (NC) in cooperative communications (CC). Prior studies have shown that NC has the potential to improve the performance of CC when there are multiple sessions in the wireless network. These studies were done for the case when multiple sessions are sharing a single relay node. However, how NC-CC behaves when multiple...
Mesh Wireless Local Area Network (WLAN) is a promising access network to enhance channels utilization, extend access coverage with simple and cheap network components. Power management affects mesh WLAN network coverage, topology, throughput, traffic routing and end to end delay. In this paper, power management problem is formulated to show its impact on mesh WLAN network throughput. Then this formulation...
In this paper, we propose a distributed throughput-optimal ad hoc wireless network scheduling algorithm, which is motivated by the celebrated simplex algorithm for solving linear programming (LP) problems. The scheduler stores a sparse set of basic schedules, and chooses the max-weight basic schedule for transmission in each time slot. At the same time, the scheduler tries to update the set of basic...
Scalable video applications have been gaining popularity during last years. Providing high quality video over wireless networks towards heterogeneous receivers is a challenging task due to erratic and time-varying nature of a wireless channel. Compressed video bit-streams, such as Scalable Video Coding (SVC), are very vulnerable to channel disturbances when transmitted over error-prone wireless channels...
The capacity of a wireless network could be considerably improved by employing directional antennas that are capable of illuminating multiple beams toward different directions. However, more beams from the same BS may lead to stronger inter-cell interference. In this paper, we consider coordinated beam scheduling schemes to mitigate the inter-cell interference. We first formulate this problem as a...
Optimizing information flow in a dense wireless network using discrete methods can be computationally prohibitive. Instead of treating the nodes as discrete entities, these networks can be modeled as continuum of nodes providing a medium for information transport. To model information routes in continuous space, information flow vector field is defined over the geographical domain of the network....
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