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In this paper we develop a framework for distributed power control in a wireless network where femto and macro cells co-exist and interfere with each other. In order to ensure a minimum QoS, femto and macro access points have the challenging and realistic objective of minimizing their users' SINR (Signal to Interference and Noise Ratio) outage. Furthermore, due to mobility and interference, an accurate...
We establish the degrees of freedom of the X-channel with delayed channel knowledge at transmitters (i.e., delayed CSIT), assuming linear coding strategies at the transmitters. We derive a new upper bound and characterize the linear degrees of freedom of this network to be 6/5. The converse builds upon our development of a general lemma for wireless networks consisting of two transmitters and two...
With recent advances in wireless systems, wireless in-band full duplex is proven possible. Prior work primarily allows a full duplex receiver to either send back a packet (bi-directional mode) or to forward another packet to its neighbor (secondary transmission). In our work, we look beyond a node pair and explore how a network can best utilize the full duplex capability. When a full duplex receiver...
In this paper, cooperative multicast with the help of short-range data sharing is studied in the cognitive radio networks (CRNs). The original multicast data is split into many segments, and the transmission of each segment is divided into two stages. In the first stage, cognitive base station transmits each segment to the corresponding cooperative user, and in the second stage, the cooperative user...
Cognitive Radio is a promising concept that offers solution to spectral crowding problem by introducing opportunistic usage of the unoccupied licensed frequency bands. Improving the network capacity and reliability of the communication has been recently studied and this through the introduction of cooperative technology in the CR networks. Furthermore, OFDM system is considered to be a good candidate...
Register allocation is one of the most time-consuming parts of the compilation process. Depending on the quality of the register allocation, a large amount of shuffle code to move values between registers is generated. In this paper, we propose a processor architecture extension to provide register file permutations by which the shuffle code can be implemented more efficiently. We present compiler...
In this paper, we propose an effective user association rule for resolving the unbalanced loading problem in multi-cell cellular networks. We first derive an improved user throughput estimation formula for the proportional fair (PF) scheduling algorithm under the Rayleigh fading environment. Our simple and accurate throughput estimation can be regarded as an extended version of the conventional scheme...
For a downlink of Multiuser (MU) Multiple-Input, Multiple-Output (MIMO) system with 2 transmitting antennas at the base station and N receiving antennas at each user, in this paper, new decoding methods, named as affine projection decoders, will be proposed and illustrated based on the Almouti scheme, under assumptions that the transmitter does not have channel state information (CSI), and transmits...
This paper considers a fully-connected interference network with a relay in which multiple users equipped with a single antenna want to exchange multiple unicast messages with other users in the network by sharing the relay equipped with multiple antennas. For such a network, the optimal degrees of freedom (DoF) are derived by providing both converse and achievability. Further, considering single-antenna...
Conditions are derived on the interference channel with single-antenna nodes to achieve maximal degrees-of-freedom with only two symbol extensions. The conditions for line-of-sight channels involve choosing only the spacing between two subcarriers of an orthogonal frequency division multiplexing (OFDM) scheme. For 3 user pairs an upper bound on the sum-rate of interference alignment is approached...
In this paper, we consider the problem of distributed power control for multiple access channels when energy-efficiency has to be optimized. In contrast with related works, the presence of a queue at each transmitter is accounted for and globally efficient solutions are sought. To this end, a repeated game model is exploited and shown to lead to solutions which are distributed in the sense of the...
Consider a wireless network of transmitter-receiver pairs. The transmitters adjust their powers to maintain a particular SINR target at the corresponding receiver in the presence of interference from neighboring transmitters. In this paper we analyze the power vector that achieves this target (and hence is optimal) in the presence of randomness in the network. The randomness is realized by randomly...
Recently, compressive sensing (CS) methods have been considered to improve the accuracy of channel estimation. Since the accurate estimation of the channel relies on the size of the observations, the fixed size of the observations is usually the trade-off between the channel estimation accuracy and the length of the channel delay to handle. In this paper, an adaptive compressive sensing (A-CS) algorithm...
This paper investigates the degrees of freedom (DoF) of the two-cluster multi-way relay channel. Two cases are investigated: the case when there are 2 users in each cluster with arbitrary number of antennas and the case when there are 3 users in each cluster in the symmetric setting, i.e., all the users have the same number of antennas. For the 2-user case, a DoF upper bound is derived based on cut...
A k-user parallel concatenated code (PCC) is proposed for a Gaussian multiple-access channel with symbol synchronization and equal power users. In this code, each user employs a PCC with M + 1 component codes, where the first component code is a rate 1/q repetition code and the other M component codes are the same rate-1 convolutional code 1/1+D. The K-user PCC achieves a larger maximum sum rate,...
A novel channel detection timing scheme for periodic sensing is proposed to minimize the sensing cost of the secondary users while protecting the transmission of the primary users. The framework consists of a Cognitive Radio Network where secondary users operate in a periodic fashion while the primary users operate in continuous-time. The scheme has been presented for both non-erroneous and erroneous...
In this paper, the problem of location classification in OFDMA-based FFR systems is considered for two FFR schemes, namely Strict FFR (FFR-A) and Soft Frequency Reuse (FFR-B). The FFR systems considered in the literature are mostly studied with static resource partitioning where a greater portion of the sub-carrier resources are reserved for users in the cell centre and a smaller portion for users...
In this paper, we address the problem of channel assignment considering partially overlapping channels (POCs) for interference avoidance in 802.11-based wireless mesh networks. A novel interference model is proposed which provides a systematic approach of measuring the interference caused by links operating on POCs by taking into account both the adjacent channel interference and the corresponding...
In this paper, direct optimization approaches are proposed for minimizing the inter-symbol interference (ISI) and the inter-carrier interference (ICI) caused by a truncated prototype filter. Based on the ideal ISI-free and/or ICI-free conditions in the transformed domain, one can define the ISI and/or ICI cost functions of the time-domain samples of the prototype filter. Using the variation technique,...
Microsoft Kinect cameras provide a fast and convenient way to acquire depth information. However, the interference problem of multiple Kinect cameras dramatically degrades the depth quality. In this paper, we study the interference problem and propose an interference cancelation approach based on the statistical properties of depth maps. The gradient values are investigated and propagated from the...
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