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The performance of a cognitive radio based Transmitter Pre-processing (TP) assisted Multi-Carrier (MC)-Code Division Multiple Access (CDMA) system over correlated frequency-selective channels for downlink communication is presented in this paper. The Singular Value Decomposition (SVD) helps us understand the need for TP. Channel State Information (CSI) is collected via feedback channels and this SVD...
In this paper, we introduce a model for Multiple-Input Multiple-Output (MIMO) Space Division Multiple Access (SDMA) into the analysis of a multi-hop millimeter wave network under the classic Network Utility Maximization (NUM) framework with Maximum Back Pressure scheduling (MBP). We show that the proof of convergence of MBP remains valid when we allow the scheduler to select multiple links to the...
This paper considers three aspects of Massive MIMO (multiple- input multiple-output) communication networks that have received little attention in previous works, but are important to understand when designing and implementing this promising wireless technology. First, we analyze how bursty data traffic behaviors affect the system. Using a probabilistic model for intermittent user activity, we show...
The centrality of interleavers in interleave-division multiple-access (IDMA) cannot be over-emphasised, the interleaver being the only means of isolating signals for different users of the multiple-access system. This work gives a critical review of bit-error-rate (BER) performance of interleavers and IDMA systems. Existing literature shows that there are disagreements among results published by different...
As a natural limited resources, the radio frequency spectrum should be managed and used as efficiently as possible. The Government as regulator has a responsibility to manage and regulate the spectrum to prevent interference. One example of the many problems in Indonesia that must be solved is the spectrum in 2.1 MHz frequency band for 3G services. The CDMA 2000 and UMTS system occupy adjacent band...
Traditional algorithms for Media Access Control (MAC) in Mobile Ad Hoc Networks (MANET) such as CSMA-CA allow only a single user to transmit at a given time. This means that the sum throughput in a MANET cannot increase to service additional users. Such MAC protocols disregard the possibility that by utilizing multiple antenna processing to handle interference intelligently at the Physical layer (PHY),...
It is shown that implementation of the method of space-time division multiple access with the individual space-time processing of subscriber stations signals which is reduced to the use of group elements of adaptive antenna array and the establishment of parallel procedures of assessing values of vector of weighting coefficients on the number of simultaneously working stations.
With the exponential growth of wireless data demand and the increasing scarcity of licensed spectrum, mobile network operators are considering extending the use of Long Term Evolution (LTE) into the unlicensed spectrum to offload their traffic. In the future, it is very likely that LTE will coexist with WiFi on the same unlicensed bands, such as the Industrial, Scientific and Medical (ISM) bands....
Military communications face increasingly congested environments requiring spectrally efficient approaches capable of contending with many users and interference. We evaluate the over-the-air performance of recently designed minimum total squared correlation (MinTSC) signature sets compared to maximal length pseudorandom binary spreading sequences (m/PN) under a variety of interference conditions...
In this paper, we consider the low probability of intercept (LPI) property of the binary Sidel'nikov sequences. We derive the LPI property of the sequences by deriving the triple autocorrelation bound of the binary Sidel'nikov sequences. The derived bound is approximately twice of square root of the period of the sequences, which is similar to that of the binary Legendre sequences.
Spread spectrum (SS) modulation is one of the most commonly used methods for data hiding. However, the capacity of SS-based methods is rather limited. To improve the hiding efficiency, this paper presents a method that employs the parallel combinatory spread spectrum (PCSS), in which the hidden data can be transmitted in parallel with a combination of a few pseudo noise sequences. An informed embedding...
Combating interference is an important yet challenging issue for multiuser communications especially in the harsh underwater acoustic environment. In this paper, a novel Angle-Of-Departure (AOD)-based technique is proposed, which accounts for the inherent position uncertainty of underwater propeller-driven Autonomous Underwater Vehicles (AUVs) or buoyancy-driven gliders. A new probabilistic Space...
This paper presents a frequency/time hopping (FH/TH) system which is used in airborne data link. Taking FH/TH system can effectively solve the near-far problem, which reduces the data collision between users. This paper constructs a long cycle frequency/time hopping sequence by using the longest linear feedback shift register sequence (m sequence), which can meet the requirement of data privacy in...
In modern communication era wireless communication devices play very important role. The demand of wireless devices are increasing day by day, as they are becoming omnipresent in communication system. These wireless devices are energy limited because it needs high amount of information. This constraint degrades the two design parameters i.e. power efficiency and production cost of the system. We can...
In this paper we present a mean-field hardcore model of interference in wireless networks using CSMA. We consider d-regular random graph ensembles in which the edges are drawn randomly and an edge in a graph represents hard-core interaction such that the two nodes connected by the edge cannot be simultaneously active, or transmitting. We present an analysis of average activity in the presence of hard-core...
In this paper, we consider an adaptive CSMA based scheduling algorithm for a single-hop wireless network under a realistic SINR (signal-to-interference-plus-noise ratio) model for the interference, and propose an efficient local optimization based algorithm to estimate certain parameters of the algorithm called fugacities. It is known that adaptive CSMA based algorithms can achieve throughput optimality,...
We propose a simple distributed uplink power control scheme based on the Foschini-Miljanic algorithm but driven by the queue sizes of each mobile station. The resulting data rates are proportional to the queue backlog of each mobile, such that the total power consumption is equal to a target value. Using analysis we establish convergence and characterize the equilibrium, and use simulations to study...
This paper develops a modeling framework, based on stochastic geometry and queueing theory, for carrier sense multiple access (CSMA) coordinated inter-vehicle communication, with unsaturated buffers, in a multi-lane highway scenario. We show that the spectrum sensing threshold (ρth) of the CSMA protocol is a critical design parameter that imposes a tradeoff between the transmission success probability...
Wireless local area networks (WLANs) are becoming denser and thus interference-limited due to heavy traffic from a number of adjacent access points (APs) and stations (STAs). We propose a novel interference management technique for overlapping basic service sets (OBSSs) in such WLANs, which intelligently applies an opportunistic interference alignment (OIA) concept to WLANs. Each BSS has an AP and...
In WLANs, collision-free communication is desired for real-time wireless video transmission (WVT) systems. A polling-based access scheme enables quality of service (QoS) and priority control over legacy WLAN stations (STAs). However, when multiple moving basic service sets (BSSs) are operating nearby in a polling-based access scheme, signal collisions between BSSs occur, and system performance of...
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