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With the ever-growing demands of wireless communications, traffic load sharing is essentially important to provide consistent high quality of service (QoS). It is known that the QoS of mobile users is affected by the limited bandwidth in both wireless link and wired backhaul link beyond a base station (BS). Femtocell is a promising technology to bear part of the traffic load from the BS. Nonetheless,...
There is substantial and growing motivation to deploy wireless relays in 3G+ and 4G networks both in residential and commercial contexts to achieve significant coverage extension and capacity increases at potentially relatively low cost. However, relays operating in shared spectrum may introduce interference thus potentially counterbalancing gains, and conversely, relays requiring a dedicated resource...
In this paper, we investigate secrecy capacity of a cognitive radio network based on stochastic geometry distributions. We consider the Poisson process of both the secondary users and the eavesdroppers, and analyze how the stochastic interference from the secondary users can influence the secrecy capacity of the primary users. First, we describe a network model with primary users, secondary users...
The use of multiple packet reception (MPR) can alleviate congestion in multi-hop networks and improve network Goodput. However, a sophisticated design is required in order to enable MPR in such networks considering the heterogeneity of transiting packets, both in size and arrival times. In this paper, we introduce a cross-layer MPR-PHY/MAC design suitable for multi-hop ad-hoc networks. Our design...
In this paper, a new distributive heuristic algorithm is developed for maximizing the network throughput in adaptive power and rate spatial-TDMA networks. At each step of our algorithm, the link with highest current receive-SINR in its 2-hop neighborhood is included in the schedule for the underlying time slot, configuring its Modulation/Coding Scheme so that it transmits at the highest feasible power...
This paper considers the problem of resource allocation for a large-scale wireless network consisting of multiple amplify-and-forward cooperative systems. The traditional competitive design leads to a network collapse where every system obtains almost zero throughput. We resolve this issue by resorting to the novel economic model of coalition formation with externalities by first letting the systems...
Compressive sensing (CS) provides a new paradigm for efficient data gathering in wireless sensor networks (WSNs). The theory of CS allows to reconstruct all sensor data of the network, while only collecting a small number of measurements at a sink. In this paper, we consider a scenario where a sink collects spatially correlated sensor data from sensor nodes randomly deployed in a region. We investigate...
Linear detectors such as zero-forcing (ZF) and minimum mean square error (MMSE) require only a small fraction of computational complexity compared to maximum likelihood (ML) detector. However, linear detections suffer from severe performance degradation. In this paper, we propose a novel detection scheme which obtains the initial symbol detection by MMSE detector and then perform symbol ordering by...
Cooperative Network-Coded Hybrid ARQ (Coop-NC HARQ) has recently been proposed as a smart way to improve Decode & Forward (D&F) relaying. According to this idea, cooperators send HARQ redundancy on behalf of a source coded together with a data packet intended for the destination they are helping and taken from their own queue. This paper applies for the first time such a technique in ad hoc...
One of the major challenges in the medium access control (MAC) protocol design over cognitive Ad Hoc networks (CAHNs) is how to efficiently utilize multiple opportunistic channels, which vary dynamically and are subject to limited power resources. To overcome this challenge, in this paper we first propose a novel diversity technology called Channel-Aggregation Diversity (CAD), allowing each secondary...
We propose an interference avoidance architecture using uneven spreading as a media access mechanism for optical code division multiple access (OCDMA). While an equal-intensity pulse sequence encoded with the spreading sequence assigned to each node is transmitted for a ``1'' bit in conventional OCDMAs with on-off keying (OOK), in our proposed architecture an uneven-intensity pulse sequence is done...
We study the sum capacity of multiple unicasts in wireless multihop networks. With 2 source nodes and 2 sink nodes, there are a total of 4 independent unicast sessions (messages), one from each source to each sink node (this setting is also known as an X network). We explore the degrees of freedom (DoF) of wireless multihop X networks with a layered structure, allowing arbitrary number of hops and...
Wireless secrecy is becoming crucial in many commercial and governmental sectors. In this paper, the secrecy capacity of a wireless channel is analyzed in the presence of intentional network interference for denial of eavesdropping capability (DEC). We propose two different DEC strategies employing the closest interferer and the multiple interferers. We show the impact of the network interference...
Relays are used in the current standards to enhance the cell throughput and coverage. Often, the relays are evaluated without considering the overhead involved in providing the relay with the data prior to the transmission. In this paper, we evaluate the system performance by considering the duplexing loss with over- the-air transmission (OTA) for relay with decode and forward as the relaying protocol...
Given the ever-increasing popularity of wireless body area networks (WBANs), in some application scenarios, many WBANs may operate densely and lead to a high mutual interference. Excessive interference may severely degrade the network performance, which is called the network co- existence problem. It is critical to fully understand the network co-existence problem to ensure the effectiveness and efficiency...
Defined for low-rate, low-power and short-range applications, IEEE 802.15.4 offers complementary services to IEEE 802.11 and IEEE 802.15.1. However, since IEEE 802.15.4-based wireless personal area networks (WPANs) are very prone to interference, efficient coexistence of IEEE 802.15.4 WPANs in the ISM band is a challenging problem. In this work, we propose a distributed coexistence method for IEEE...
In recent years, wireless mesh networks (WMNs) have attracted considerable interest from both academia and industry. WMNs offer attractive advantages such as easy installation, fast deployment, and low operating expense. For this reason, many cities and network operators have built WMNs to provide wireless Internet access in metropolitan areas. Despite their advantages, WMNs face numerous challenges...
Heterogeneous cellular networks have emerged as a new paradigm in the wireless network to increase cellular capacity and coverage. Future heterogeneous networks will have a mixed deployment of high power and low power nodes. This creates complicated interference scenarios that require more tight resource coordination among neighbouring nodes than in the traditional cellular networks. In this paper...
In this paper, we investigate the impact of relay cooperation for maintaining coverage area against aggregate interference from incumbent underlaid interferers. We employ a guard zone for uplink so that non-urgent interferers are inhibited and urgent ones are admitted with a controlled access probability as long as the primary receiver can tolerate. Numerical results show the outage probability of...
Traffic Engineering application to the cross-layer design of Multiple Access Interference (MAI)-affected powerlimited wireless networks, when Quality of Service constraints are also present, leads to deal with nonconvex resource allocation problems. Although several manageable-complexity solutions have been proposed, they are based on specific capacity functions and, generally, fail to provide reliable...
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