Neeraj Varshney

Selective DF Protocol for MIMO STBC Based Single/Multiple Relay Cooperative Communication: End-to-End Performance and Optimal Power Allocation

In this paper, we consider the performance of a selective decode-and-forward (DF) relaying based multiple-input multiple-output (MIMO) space-time block coded (STBC) cooperative communication system with single and multiple relays. We begin with a single relay based MIMO STBC system and derive the closed form expression for the end-to-end PEP of coded block detection at the destination node. It is also demonstrated that the MIMO STBC cooperative communication system achieves the full diversity order of the system. We also derive the optimal source relay power allocation, which minimizes the end-to-end decoding error of the cooperative system for a given power budget. Subsequently, for the multiple relay scenario, we consider two different relaying protocols based on two-phase and multi-phase communication. For each of these multi-relay protocols, we derive the closed form expressions for the end-to-end error rate, diversity order, and optimal power allocation. Simulation results are presented to validate the performance of the proposed single and multiple relay based cooperative communication schemes and the derived analytical results. Further, these schemes can also be seen to lead to a performance improvement compared to several other relaying schemes in existing literature.

An adaptive notch filter for narrow band interference removal

A modification on an existing algorithm to dynamically adapt to interfering signal frequency and its magnitude is given. The algorithm first detects the presence of the interfering signal in real time and if present, it adjusts parameters to maximize the signal to noise ratio at the output. The AWGN and interfering signal power is taken in a wide dynamic range - up to 20 dB and 80 dB respectively. The proposed IIR filter detects and almost perfectly removes the interference.

Capacity analysis for MIMO beamforming based cooperative systems over time-selective links with full SNR/one-bit feedback based path selection and imperfect CSI

This paper presents an analysis for the ergodic capacity of a multiple-input multiple-output (MIMO) beamforming based cooperative wireless communication system considering the effect of node mobility and channel estimation errors. Closed form expressions are derived for the ergodic capacity of a path selection based decode-and-forward (DF) relaying protocol considering the availability of both full SNR and only one-bit feedback for path selection. Simulation results are presented to illustrate the impact of node mobility and imperfect channel estimates on the ergodic capacity of the MIMO beamforming based DF cooperative path selection scheme and verify the analytical results derived.

Cooperative communication in spatially modulated MIMO systems

This paper analyzes the performance of a selective Decode-and-Forward (DF) protocol based cooperative space-time block coded spatial modulation (STBC-SM) MIMO system. Further, the analysis is presented for a Kronecker MIMO channel model considering spatial correlated channel conditions. The results are also derived for the diversity order of the system based on a high signal to noise ratio (SNR) characterization of the performance followed by the optimal power allocation between the source and relay. Simulation results demonstrate that the proposed scheme achieves a lower pair-wise error probability (PEP) in comparison to other schemes such as the conventional cooperative Alamouti-STBC and non-cooperative transmission.

Cognitive Decode-and-Forward MIMO-RF/FSO Cooperative Relay Networks

This letter considers decode-and-forward (DF) based mixed multiple-input multiple-output radio frequency/free space optical (MIMO-RF/FSO) cooperative relay systems for underlay cognitive radio scenarios. Subsequently, a performance analysis is presented and closed-form expressions are derived for the per-frame outage probability considering both orthogonal space-time block coded transmission and transmit antenna selection at the secondary user. The analysis assumes the RF links between the secondary user-relay and secondary user-primary user to be Nakagami-

Capacity Analysis for Path Selection Based DF MIMO-OSTBC Cooperative Wireless Systems

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Performance Analysis of Decode-and-Forward-Based Mixed MIMO-RF/FSO Cooperative Systems With Source Mobility and Imperfect CSI

fading in nature, while the FSO link between the relay and destination eNodeB is assumed to be affected by optical channel impairments, such as path loss, atmospheric turbulence, and pointing errors, thus incorporating the key characteristics of both the links. Further, the impact of primary user node mobility on the performance of the cognitive radio network is also analyzed. Results demonstrate an improved outage performance of the cognitive MIMO-RF/FSO DF cooperative relay system with multiple antennas in comparison to amplify-and-forward based single-input single-output systems proposed in the existing literature.

Outage analysis for path selection based MIMO-beamforming cooperative wireless systems with node mobility and imperfect CSI

In this paper, we analyze the ergodic capacity of a path selection based Decode-and-Forward (DF) MIMO-OSTBC cooperative wireless system. Closed form expressions are derived for the ergodic capacity considering the availability of full as well as partial CSI at the source. Simulation results are presented to demonstrate the ergodic capacity of the MIMO-OSTBC DF cooperative relaying system and verify the analytical expressions derived. Interestingly, it is observed that while the availability of full CSI at the source generally leads to a higher capacity, its performance gain over the scenario with partial CSI is only marginal when either the source-destination or source-relay link is relatively strong.

Performance analysis of MIMO-OSTBC based selective DF cooperative wireless system with node mobility and channel estimation errors

This paper investigates a decode-and-forward-based asymmetric dual-hop mixed radio-frequency/free-space optical (RF/FSO) communication link. We consider a moving source user equipment (UE) that communicates with the relay over an RF link and the relay communicates with the serving base station (eNodeB) over an FSO link, assuming there is no direct link between the UE and eNodeB. It is assumed that the source-to-relay link experiences time-selective Rayleigh fading, that arises due to the UE mobility and the relay-destination link is affected by the optical channel impairments, including path loss, atmospheric turbulence, and pointing errors. As the FSO link has a higher data rate in comparison to the RF link, we employ multiple-input multiple-output with zero-forcing (ZF) based linear receiver in the source-to-relay link, in order to enhance the RF link data rate without increasing the transmit power and bandwidth requirements. Moreover, we assume that the relay node has imperfect channel state information (CSI) for the ZF decoding. For the considered system and channel models, novel closed-form expressions for the per-frame average outage probability, bit error rate, and ergodic capacity are derived and verified using Monte Carlo simulations. Additionally, asymptotic floors for the system outage and error probabilities are derived. It is observed that the time-varying nature of the RF link and imperfect CSI at the relay significantly degrades the end-to-end performance of the system.

A Unified Framework for the Analysis of Path Selection Based DF Cooperation in Wireless Systems

This paper presents an analysis for the end-to-end SNR outage probability of a multiple-input multiple-output (MIMO) beamforming based cooperative wireless communication system considering the effects of node mobility and channel estimation errors. Closed form expressions are derived for the per-block SNR outage probability as well as the asymptotic outage floor. Simulation results illustrate the outage performance of the MIMO beamforming based DF cooperative path selection scheme under various node mobility scenarios and verify the analytical results derived. Interestingly, it is observed that except for scenarios in which only the relay node is mobile with static source and destination nodes, the system always experiences an asymptotic error floor with SNR due to node mobility.