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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...
An effective joint radio-frequency (RF) and baseband (BB) hybrid beamforming (HBF) scheme is presented for two-user spatial division multiple access (SDMA) in 60GHz radio using planar antenna arrays (PAA). Taking into account the physical constraints of the phase shifters of PAA, we study the design of downlink HBF from two perspectives of conic optimization: transmit power minimization subject to...
In this paper, we propose smart step closed-loop power control (SSPC) algorithm in a direct sequence-code division multiple access (DS-CDMA) receiver in the presence of frequency-selective Rayleigh fading. This receiver consists of three stages. In the first stage, with conjugate gradient (CG) adaptive beamforming algorithm, the desired users' signal in an arbitrary path is passed and the inter-path...
In this paper, we analyze the interference distribution and gain of beamforming in closed access femtocells in downlink of a two-tier HSDPA cellular network. We show through simulations that indoor femtocell deployment leads to a dominant interferer scenario. According to results even simple null steering method based on the scarce codebook of HSDPA transmit diversity mode 1 can be beneficially applied...
This paper presents a time-efficient optimal resource allocation algorithm aiming to maximize the system throughput of the single-user High Speed Downlink Packet Access (HSDPA) deployed in a femtocell base station. The system throughput maximization with constrained total power is formulated as a constrained integer programming problem. We first prove that a two-group bit and energy allocation provides...
Wireless relay is an essential technology to achieve a flexible network for ubiquitous communication. To improve throughput performance in the network, network coding (NC) has been proposed for a two-user relay node. NC is a concept encoding both users' data into one packet and multicasting it simultaneously. However, if the relay node has two or more antenna elements, antenna pattern control is additionally...
In this paper, we present a multistage group-decision-aid MUD (MG-MUD) for the uplink multirate code division multiple access (CDMA) systems. To provide good tradeoff between the performance and computational complexity, the new MUD is based on the widely MMSE criterion and constructed by a bank of group detectors in each stage. First, the users are classified into different groups according to their...
This paper addresses the stability of a multi-antenna space division multiple access (SDMA) system that uses zero-forcing beamforming to support packet data services for a small number of mobiles. Define the stability region as the set of packet arrival rates for which finite queue lengths are feasible in the steady state. Consider perfect feedback of channel state information (CSI) and equal power...
Compressed sensing deals with the reconstruction of a high-dimensional signal from far fewer linear measurements, where the signal is known to admit a sparse representation in a certain linear space. The asymptotic scaling of the number of measurements needed for reconstruction as the dimension of the signal increases has been studied extensively. This work takes a fundamental perspective on the problem...
With the development of wireless and mobile Internet technology, people in everyday life and business hope for access to the Internet even while they are in movement. IEEE 802.20 technology is mobile and can effectively address high-speed network access. In this paper the PHY layer model for simulating 802.20 in SIMULINK and subsystems in MATLAB S-function files are presented. To evaluate the performance...
This paper proposes RADICAL independent component analysis (ICA) algorithm for detection of DS-CDMA signals and also effect of fading on ICA based detection of DS-CDMA has been studied. ICA based technique is based on independence of source signals and these conditions are satisfied in multi-user CDMA environment. Combining an ICA element to conventional signal detection reduces multiple access interference...
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