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Inbound handover (HO) or hand-in is accomplished when the user equipment (UE) performs HO from macrocell (MC) to a small cell (SC) [1] [2]. When the UE connects to a SC with a time of stay (ToS) less than a predefined time threshold, this will result in frequent unnecessary HOs and also increase service interruption which in turn will degrade the end user quality of service (QoS). In this paper, we...
With the presence of noise floor, characteristic points of signals are submerged easily in conventional cyclostationary feature detection. In this paper, a new cyclostationary feature detection method based on the correlation between signal and noise is proposed for detection of OFDM based primary users. The proposed scheme aims to improve the noise robustness through making the utmost of the information...
In this paper, we consider the problem of direction of arrival (DOA) estimation achieved by a distributed way in wireless sensors networks. The goal for each node is to detect targets based on its local information and that of its neighbors through some iteration. Classic estimation methods, such as maximum likelihood (ML) algorithm, are not suitable here because there is often a requirement of a...
In this paper, we consider a worst-case based robust beam forming approach for two-way relay networks that consist of two transceivers and multiple relays. Both the transceiver-to relay channels are assumed to have norm-bounded channel estimation errors. The worst case of the problem in a norm defined error set is optimized to guarantee the performance of the actual case. The resultant beam forming...
In this paper, we propose a spectrum splitting-based cognitive interference management method for LTE downlink two-tier networks (that provide closed-access mode). In the proposed method, the resource-blocks in the macrocell (in frequency and time domain) are allocated to the users with the received signal-to-interference-plus-noise-ratio greater than a threshold. The rest of resource-blocks are then...
This paper explores the symbol synchronization in the presence of co-channel interference (CCI) of Orthogonal Frequency Division Multiplexing (OFDM) based heterogeneous network (HetNet). The CCI is generated by a HetNet model with macrocell and small cells. Schmidl and Cox (S&C) Algorithm is applied for symbol synchronization. We find that the presence of CCI severely degrades the performance...
The impact of downlink co-channel interference (CCI) is increasingly highlighted in heterogeneous networks (Het-Nets) where the macrocell base stations (MBSs) and low-power nodes share the same spectrum resource. In this paper, we focus on mitigation of downlink CCI from MBS to picocells, which are severely affected, through the application of coordinated beam forming (CBF) technique. The closed-form...
Energy detection (ED) is a simple and popular method of spectrum sensing in cognitive radio systems. It is also widely known that the performance of sensing techniques is largely affected when users experience fading effects. This paper investigates the performance of an energy detector over generalized and extreme fading channels, which have been shown to provide remarkably...
In this paper, a maximum a posterior (MAP) based channel estimation algorithm is proposed to estimate both the temporal and spatial domain channel parameters for single-input multiple-output (SIMO) systems transmitting over an extended Saleh-Valenzuela (SV) channel. The proposed algorithm leverages on prior knowledge of the statistical distributions of signal clusters and rays within a cluster, and...
According to the characteristic that the surface electromyogram signal (sEMG) is very weak and influenced by noise vulnerability, this paper proposes a new method that uses the unsupervised Kohonen neural network weights optimized to determine the order of the reconstruction matrix during the process of the noise reduction in singular value decomposition (SVD) effectively. First, let the sEMG collected...
A novel distributed Raman amplification based on Random Distributed feedback fiber laser (RDFB-FL) is proposed for the first time. The experimental results confirmed its unique ultra-low intensity noise performance for the proposed distributed amplification. We also provided a new fully distributed measurement method for optical signal-to-noise (OSNR) based on stimulated Brillouin scattering for the...
We propose a scheme of utilizing multilevel space-time signal-based turbo code (MST-SB-TC) for wireless communication systems with multiple antennas over very rapidly Rayleigh block fading channels where the fading coefficients changes independently for every transmitted signal. No channel state information (CSI) is available and even unitary space-time signals fail to operate. We give an effective...
This paper investigates the effect of channel estimation error (CEE) on the performance of distributed estimation of an unknown parameter in wireless sensor networks (WSNs). Firstly, considering the maximum likelihood estimator (MLE) of the unknown parameter has a high complexity preventing its practical implementation, a suboptimal ML estimator is derived as a low complexity alternative. Considering...
In this paper, we propose a novel algorithm to improve the accuracy in estimating the angle-of-arrival (AoA) when the MUSIC (MUltiple SIgnal Classification) algorithm is used. An optimal precoder, with the objective to minimize the estimation errors of the AoAs, is first derived. However, to compute the optimal precoder requires the channel state information (CSI) exclusive of the receiver array,...
In this paper, we consider interference cancellation (IC) schemes for uplink orthogonal frequency division multiple-access (OFDMA) systems with carrier frequency offsets (CFOs). To improve the detection performance without increasing the computational complexity of the detector, we propose a low-complexity multi-stage interference cancellation (MIC) scheme based on a grouped minimum mean squared error...
In this paper, we propose a low-complexity interference cancellation (IC) scheme for OFDMA uplink systems with CFOs. The proposed scheme employs a multi-stage structure, in which a subcarrier-grouped MMSE scheme is used in each stage. To make the proposed scheme more flexible to the tradeoff between the performance and the complexity, we generalize the subcarrier-grouped MMSE scheme and employ a novel...
We consider a Decoded-and-Forward (DF) cooperative relaying network without a direct link. We investigate the outage probability (OP) of cooperation systems with either a DF scheme or a Selective DF (S-DF) scheme when relay channels experience statistically different Rayleigh fading. In the case of the DF system, an upper and lower bound of the OP are established to show the asymptotic performance...
This paper address the problem of designing jointly the linear transmitters and receiver in a non-regenerative MIMO relay system, where linear processing is applied at the source, relay and destination node, using minimum mean square error (MMSE) criterion. Under the average power constraints at both the source and relay node, the iterative optimization method is presented and a low-complexity block...
A system simulation for a high input-referred second-order intercept point (IIP2) in active mixer of direct-down-conversion (DCR) with adaptive filter calibration is proposed. According to the simulation results of Simulink, by adopting the RLS filter calibration, a DCR mixer working under GSM 900 can achieve an IIP2 enhancement from 53dBm to over 70dBm within 0.3ms. The comparisons between RLS and...
Multimedia Broadcast/Multicast Service (MBMS) based on point-to-multipoint (p-t-m) radio transmission was introduced by 3GPP to deliver broadcast service to a group of user equipments (UEs) in a cellular system. As a broadcast system with uplink feedback, its performance is limited by UEs in poor connections. To utilize the limited radio resource more efficiently, a simple but effective mechanism...
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