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Maintaining permanent availability and high quality connection to desired networks are amongst the essential concerns of heterogeneous networks considering user criteria. In this direction, suggesting solutions to decrease the processing delay and the number of extra vertical handovers of the SAW and TOPSIS through proposed techniques are the main purpose of this paper.
In this contribution, multi-user Space-Time Block Coding (STBC) Code Division Multiple Access (CDMA) system is simulated to investigate the effect of multi-user interference along with the spatial correlation of Multiple-Input Single-Output (MISO) channels. The correlative model is considered for MISO channel. Simulation results declare that spatial correlation degrades the performance of STBC CDMA...
In this paper the effect of spatial correlation in code division multiple access (CDMA) space-time block coding (STBC) system is investigated. Having some information about the channel of each active user in the transmitter, a linear precoder can be exploited in downlink situation to mitigate the effect of correlation in multiuser system environment which has not been addressed before. Simulation...
Since bandwidth is the most critical resource in mobile cellular networks, it is important to employ mechanisms for efficiently using the available bandwidth. Mobility of users and scarcity of bandwidth makes QoS provisioning a difficult task in cellular networks. In this paper, a call admission control (CAC) and resource reservation mechanism (RR) is described to provide a consistent QoS guarantee...
In this contribution, Space-Time Block Coding (STBC) Code Division Multiple Access (CDMA) system is simulated to investigate the effect of spatial correlation of Multiple-input multiple-output (MIMO) wireless channels. In practical situations the MIMO antennas are spatially correlated, due to the lack of spacing between them or weak scattering. The correlative model is considered for MIMO channel...
Rate control is an important issue for video streaming in cellular networks. This paper describes an equation based rate control for video streaming over cellular networks. In our method, the sending rate is calculated as a function of round trip time (RTT), loss event rate (p), packet size (s) and new control parameters alpha and beta that are able to provide flexible and smooth transmission rate...
In radar signal processing distinction of false targets from real targets and fixing their rate in different radar environments is desirable. In this paper, at first, switching constant false alarm rate (S-CFAR) processor has been improved to achieve Improved SCFAR in order to fix the false alarm rate not only in homogenous environment only with thermal noise but also in non-homogenous environment,...
Rate control is an important issue for video streaming in cellular networks. In this paper, we propose an equation based rate control and multiple connections for adaptive video streaming over cellular networks. In our method the sending rate is calculated as a function of round trip time (RTT), loss event rate (p), packet size (s) and new control parameters alpha and beta, that are able to provide...
In this paper, we cast the problem of finding the capacity-achieving transmit covariance of correlated Ricean MIMO fading channels as an equivalent problem as for uncorrelated Ricean MIMO channels. Perfect channel information is assumed to be available at the receiver, while the transmitter only has channel distribution side information. An iterative algorithm based on Newton method to compute the...
The impulsive UWB pulses require extremely high sampling rates as well as accurate timing synchronization. Such coherent transceivers as RAKE are too complicated for current applications. The low complexity receiver provides the first commercially feasible solution to a broad class of low-data-rate applications. One approach is time reversed UWB communication as an alternative to coherent reception...
In this paper, we derive an exact closed-form expression for the ergodic capacity of an i.i.d. Rayleigh fading MIMO channels when the transmitter has no channel knowledge (no CSIT) and when transmitter has channel distribution side information (CDIT). This new expression is in terms of the sum of two polynomials that one of them is multiplied by the exponential integral. The coefficients of these...
In this paper, we derive a closed form necessary and sufficient condition under which rank r multichannel beamforming achieves the capacity of a single user spatially correlated Rayleigh fading channel which employs multiple transmit antennas and a single receive antenna. It is assumed that the receiver has perfect channel side information (CSIR) while the transmitter only knows the channel distribution...
In this paper, Cramer-Rao bound (CRB) for joint carrier frequency and symbol timing offsets and channel taps is proposed for multi carrier code division multiple access (MC- CDMA) systems. CRB provides a benchmark by which, the performance of any unbiased estimator can be compared. Minimum variance unbiased (MVU) estimator is the one that attains the CRB for all values of the unknown parameter. We...
In radar signal processing distinction of false targets from real targets and fixing their rate in different radar environments is desirable. In this paper, the Switching Constant False Alarm Rate (SCFAR) processor has been improved in order to fix the false alarm rate not only in a homogenous environment only with thermal noise but also in a non-homogenous environment, consisting clutter edge and...
In radar signal processing, distinction of false targets from real targets and fixing their rate in different radar environments is desirable. In this paper, performance of improved switching constant false alarm rate (ISCFAR) in homogenous and non-homogenous environments consisting clutter and multiple targets in comparison of conventional CFAR processors is derived. The results of detection and...
In this paper, we formulate the SINR-constrained power allocation problem in the wideband multiantenna CDMA cellular system as a game. Using the cooperative theory and Nash bargaining model, we compared it to the noncooperative game scheme proposed in (S. Koskie, Z. Gajic, IEEE trans. on Networking, 2005). We define a utility function which considers both power usage and QoS. We show that the resulting...
Data transmission in impulsive noise channel such as mobile, power line communications, ADSL, etc. needs error correction techniques. In error correction codes, Turbo codes have a performance that approaches the Shannon limit on the capacity of a band limited communication channel. Simulation results show that turbo codes have a good performance in this channel. Turbo code with K=4, R=1/2 and iteration=3...
In this paper, we formulate the SINR-constrained power control problem in the wideband CDMA cellular system as a game. Using the cooperative theory and Nash bargaining model, we compared it to the non-cooperative game scheme proposed in (S. Koskie and Z. Gajic, 2005). We show that the resulting operating point using Nash bargaining model is fair and Pareto optimal, however, the Nash equilibrium operating...
In this paper we have estimated signal to noise ratio (SNR) of active users in uplink scenario of CDMA systems blindly. We have not any knowledge about PN (pseudo noise) code, frequency, and timing of received signals. In this way first we synchronized received signal of desired user and then we use subspace method for SNR estimation of synchronized user. This type of SNR estimation is classified...
It is well known that the performance of OFDM systems is severely affected by the inphase and quadraure (IQ) imbalances of down converter modulators in receivers. In this paper, the effects of IQ imbalance on the performance of the OFDM systems with rectangular M-QAM constellations are investigated and a closed form of bit error rate (BER) of these systems in additive white Gaussian noise (AWGN) channels...
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