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In this paper, we present the performance of multi-antenna harmonic mean amplify-and-forward (HM-AF) relay system over independent and non-identically distributed (i.n.i.d) Rayleigh fading channels. The outage probability, moment generation function and symbol error probability are derived in closed-form using the SNR statistical characteristics. Finally, for comparison with analytical results, we...
In this paper, we present the performance of selective combining decode-and-forward relay networks in independent and non identical distributed Rician fading channels. The outage probability, moment generation function, symbol error probability and average channel capacity are derived in closed-form using the SNR statistical characteristics. After that, we analyze the outage probability at high SNR...
A daptive radio resource allocation in a cellular and multiuser OFDMA-Based relay network is considered in this paper. We solve the problem with the objective function for minimizing total transmitted power and the constraints on the relay and user data rates. We have studied adaptive subframe and subcarrier allocation and greedy bit loading in a cellular scenario. Users are distributed randomly and...
In this paper we developed a sub-optimal algorithm for joint routing and power allocation for an amplify-and-forward multi-hop relay network. The objective function for the optimization is the received signal-to-noise ratio (SNR) at the destination. Higher SNR would cause for lower bit error rate consequently. The joint problem of power allocation and relay selection is formulated with respect to...
In this paper, an adaptive resource allocation (subframe, subcarrier, bit and power allocation) in a cellular multiuser OFDMA-based relay network is considered. We have studied a margin adaptive problem that satisfies link rate requirements with minimum total base station and relay stations power for a fixed set of discrete modulation levels. This problem has been solved by various optimization techniques...
In this paper, an adaptive resource allocation (subframe, subcarrier, bit and power allocation) in a cellular multiuser OFDMA-based relay network is considered. We have studied a Margin Adaptive problem which satisfies link rate requirements with minimum total base station and relay stations power for a fixed set of discrete modulation levels. This problem has been previously solved by various optimization...
In this paper the problem of Symbol Error Rate (SER) minimization is coupled with Peak to Average Power Ratio (PAPR) reduction in Orthogonal Frequency Division Multiplexing (OFDM) systems and it is studied in one optimization problem. The deterministic function for PAPR is excluded and presented as a constraint for the main SER object function.
Considering the quality-of-service (QoS), power allocation is a critical importance issue in realizing multi-hop relay systems. In this paper considering the QoS Constraints in term of BER or instantaneous SNR, an optimal power allocation scheme that minimized the total power consumption in an amplify-and-forward (AF) multi-hop multi-branch transmission system is proposed. Considering an asymptotic...
In this paper, we have proposed an active spectrum sensing method which benefits from primary user's closed loop power control. The idea of active sensing let the cognitive transmitter to use the spectrum by estimating the maximum power of cognitive Radio transmitter that doesn't lead to harmful interference to primary receiver in the range of primary transmitter. So a cognitive radio can communicate...
Most of the current spectrum sensing methods detect primary transmitters while in proactive spectrum sensing the goal is to avoid interfering with primary receivers. In a proactive spectrum sensing approach, cognitive radio (CR) detects whether a primary receiver (PR) is within the coverage or interference range of the CR. Recent studies on spectrum sensing for CR reveal that sensing based on single...
Optimal power allocation is a critical approach to realize the full potentials of relay-assisted transmission promised by the recent information-theoretic results. In this paper an optimal power allocation scheme that maximizes the instantaneous signal-to-noise ratio (SNR) in an amplify-an-forward (AF) multi-hop multi-branch transmission system is proposed. By considering an asymptotic expression...
Ultra wideband communication is a promising technology with attractive features of low power, low complexity transceiver and rich multipath diversity that can be used for transmitting both high and low data rates. Exploiting the inherent capabilities of UWB communication is up to perfect synchronization between transmitter and the receiver which is a serious bottleneck of these systems. Using very...
In Orthogonal Frequency Division Multiplexing (OFDM) systems over fading channels, channel estimation is carried out by transmitting pilot symbols in different patterns. The process consists of two steps. First, the estimation of channel at pilot frequencies is done based on LS criteria. Then, this estimation is interpolated using linear interpolation, cubic interpolation, and spline interpolation...
A variety of results to date have expressed the advantageous of relay nodes assisting transmissions in a wireless network. In a multi-user system, not all users may wish or be able to be involved in every transmission. However, idle users can be used as a relay node in each transmission when the system requires them. In this paper we propose a new multi-user MIMO cooperative communication protocol...
In this paper, we present a cross layer protocol design for MIMO ad hoc networks. Our cross layer design resulted in a back-and-forth interaction between the PHY and MAC layers. First, we design a PHY layer by MIMO communication through spatial multiplexing and multiuser detection. After that, we design a framed MAC protocol on top of PHY layer in a cross layer fashion that works very well. Our results...
This paper describes a vector quantization of a 600 bps speech coding parameters based on the Mixed Excitation Linear Prediction (MELP) model, which was accepted as a standard in communication on narrow-band HF channels. The MELP speech coders are robust in difficult background noise environments and intended mostly for military communications. To reduce the bit rate, a joint vector quantization of...
In this paper, we start from the analysis of the performance of the PHY layer in a multiuser context and derive the implication that this PHY layer would be on the design of higher layer protocols. We continue by designing a MAC layer that makes use of back-and-forth information exchanges with the PHY layer in order to perform multiuser detection. The whole process is driven in order to guarantee...
Space-time coding is widely used in wireless communication systems to provide diversity gain and channel coding is used to increase coding gain. In this paper, we investigate a new method for turbo codes which is dividing turbo encoder and decoder into several parallel coding and decoding blocks. These blocks work simultaneously and yield to much faster coding scheme in comparison with classical turbo...
The coordination of power control and soft handover has a major effect on DS-CDMA systems. In this paper, we investigate the power controlled DS-CDMA reverse-link performance under soft handover with convolutional coding scheme. It is shown that system under soft handover has less sensitivity against incrementing the number of users. The effect of the link balance is evaluated through simulation by...
A collection of slides on concatenation of LDPC and space-time codes is given. The authors also consider wireless communications, turbo codes and simulations.
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