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TCP does not perform well in networks with stochastic channels, with links that randomly drop packets or have long outages. Diversity routing has been proposed to improve TCP's performance in these networks. In diversity routing, a sublayer between TCP and the network replicates each transmitted packet and sends the multiple copies along parallel paths. As long as at least one of the copies reaches...
This paper considers the problem of uplink scheduling in wireless networks supporting successive interference cancellation (SIC) at the physical layer. By allowing concurrent interfering transmissions, SIC enables multi-packet reception at the receiver resulting in increased network throughput. Specifically, we consider maximum throughput scheduling and proportional fair scheduling problems and study...
We consider a wireless communication model where a large number of transmitter-receiver pairs share a common Rayleigh fading channel without any coordination between them. The performance of a simple coexistence etiquette is analyzed in details, where packets are allowed to be transmitted from a given terminal only if the signal-to-interference-plus-noise ratio (SINR) at their intended receiver exceeds...
This paper describes a method to mitigate interference when the cyclic prefix (CP) is totally removed for shaped orthogonal frequency division multiplexing (OFDM) signals. The CP is removed to increase system throughput while shaping is applied to increase the spectral efficiency. Samples in the shaping extension are used to restore part of the cyclicity information missing in the ith received symbol...
Spectrum sharing has attracted a lot of attention in cognitive radio recently, as an effective method of alleviating the spectrum scarcity problem, by allowing unlicensed (secondary) users to coexist with licensed (primary) users under the condition of protecting the latter from harmful interference. In this paper, we focus on the throughput maximization of spectrum sharing cognitive radio networks...
In this paper, the fading broadcast channel with confidential messages is studied in the presence of statistical quality of service (QoS) constraints in the form of limitations on the buffer length. We employ the effective capacity formulation to measure the throughput of the confidential and common messages. We assume that the channel side information (CSI) is available at both the transmitter and...
We consider a cognitive radio network, where M distributed secondary users search for spectrum opportunities among N independent channels without information exchange. The occupancy of each channel by the primary network is modeled as a Bernoulli process with unknown mean which represents the unknown traffic load of the primary network. In each slot, a secondary transmitter chooses one channel to...
In this paper, we propose a sum rate maximizing ordering method for hard decision successive interference cancellation receiver of MIMO-OFDM systems. Compared with conventional ordering methods developed for open loop MIMO systems, the proposed scheme shows considerable improvement in throughput capacity. We propose two simplified methods with considerable complexity reduction and negligible performance...
Multiple-antenna systems have been shown to provide significant performance improvements over single-antenna systems. Theoretical analysis, simulation and experimental testing corroborate improvements in capacity and transmit power/energy savings. Unfortunately, co-located MIMO radios have numerous disadvantages compared to single-antenna radios; such as more complex RF and modem signal processing,...
Multicast is an efficient paradigm for transmitting data from a sender to a group of receivers. In IEEE 802.11 wireless LANs, multicast is specified as a simple mechanism that does not make use of ACK frames. The absence of a feedback mechanism has a strong impact on the reliability of the service provided to the user. This is particular true in a network composed of a large number of active stations...
Spread spectrum multiple-access packetized wireless communications systems are considered. Although very efficient in low traffic (or low-rate) and low signal-to-noise ratio scenarios, the traditional and well-known spread ALOHA multiple access (SAMA) quickly collapses when both traffic and signal power increase. In certain situations, such as wireless sensor network traffic towards a sink, this severely...
The congestion control scheme plays a critical role in the multicast communication. Without a proper congestion control mechanism, multicast protocols would cause unfairness while sharing network bandwidth with other flows. We propose a deliberated congestion control scheme to multicast multimedia contents for smart phones retrieving effectively. Our key idea is to detect the single trip time of packet...
This paper introduces a novel paradigm for designing the physical and medium access control (MAC) layers of mobile ad hoc or peer-to-peer networks formed by half-duplex radios. A node equipped with such a radio cannot simultaneously transmit and receive useful signals at the same frequency. Unlike in conventional designs, where a node's transmission frames are scheduled away from its reception, each...
In many wireless systems, the energy consumed by the receiver is significantly larger than the energy consumed by transmitter, possibly even by orders of magnitudes. This paper derives an analytical solution to maximize the throughput per unit of available receiver circuit power. Adaptive control of the IP3, to handle the time-varying adjacent channel interference level, can substantially improve...
A cognitive network consists of primary nodes, which have priority access to the spectrum, and cognitive (also referred to as secondary) nodes, which access the spectrum provided that the interference they generate in the primary system remains limited. In practice, it means that the cognitive terminals must remain outside of a region surrounding the primary receiver: the primary exclusive region...
In wireless ad hoc networks, multiple access interference is the limiting factor for the overall system performance. The lack of any central control unit necessitates a careful joint design of both, the physical and the MAC layer. Two promising technologies that address this problem are power control based cross-layer design and multiuser detection based cross-layer design. While approaches in the...
Vandermonde-subspace frequency division multiplexing (VFDM) is a technique for interference cancellation in overlay networks that allows a secondary network to operate simultaneously with a primary network, on the same frequency band. VFDM can be applied to block transmission systems with a guard time (or cyclic prefix) over frequency selective channels. It achieves zero interference towards the primary...
The purpose of this paper is to demonstrate the advantages of receiver based interference protection for Medium Access Control (MAC) protocols in Wireless Sensor Networks (WSNs) and to present a two-hop protection scheme which can increase the probability of successful data packet transmission. In previous studies of MAC protocols for WSNs, hop based interference models are commonly used, and the...
In this paper, we introduced an adaptive cumulative layered multicast scheme, ACLM, to address multicast receivers' heterogeneity in available bandwidth. ACLM uses an optimal layer rate allocation algorithm which can maximally satisfy each receiver's available bandwidth. Through a novel feedback aggregate algorithm, ACLM dynamically determines the number of layers and the rate of each layer. Simulation...
Maximizing the battery life time of mobile devices and sensor nodes increasingly becomes a challenge, and receiver power consumption tends to become more problematic than delivering adequate transmit power. We address the challenge of achieving the highest possible throughput per Watt of receiver circuit power. Our results show that optimum and adaptive tuning of the front-end parameters of the receiver...
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