Volkan Ozduran

Opportunistic source-pair selection for multi-user two-way amplify-and-forward wireless relaying networks

This study investigates the opportunistic source-pair selection (OSPS) strategy for the intercell interference (ICI) challenge in multi-user amplify-and-forward-based bi-directional wireless relaying networks. The method relies on selection of an appropriate SP node among N available SP nodes based on each SPs maximum sum capacity (SC). According to analytical, asymptotic and Monte Carlo simulation results, the OSPS strategy, besides achieving the near-optimal solution for the ICI challenge, if the number of the user-pair increases, also achieves multi-user diversity gain by selecting the maximum SC user-pair in each time slot. Moreover, the SC-based user-pair selection method outperforms the simultaneous transmission model and the max–min-based user-pair selection method in such a system model.

Opportunistic source-pair selection (OSPS) method for multiuser Bi-directional wireless relaying networks

This paper investigates the opportunistic source-pair selection (OSPS) strategy for the co-channel interference challenge in multiuser amplify-and-forward based bi-directional wireless relaying networks. The method relies upon selection of the appropriate source-pair node among N available source-pair nodes based on each source pairs maximum sum capacity. According to the simulation results, the OSPS strategy, besides achieving the near optimal solution for the co-channel interference challenge, and if the number of the user pair increases, also achieves multiuser diversity order by selecting the maximum sum-capacity user-pair in each time slot.

Impact of channel estimation error on physical layer security in dual-hop half/full-duplex two-way wireless relaying networks

This paper investigates the impact of the imperfect channel state information that is caused by the channel estimation errors on physical layer security. The investigation considers a dual-hop single amplify-and-forward (AF) based untrustworthy half/full-duplex bi-directional relay with a finite number of friendly jammers in the system model. According to Monte-Carlo simulation results, the channel estimation error causes system coding gain losses at low signal-to-noise ratio (SNR) regimes both for half and full-duplex cases. Results also show that the CEE effects turn out to be at negligible levels in high SNR regimes. Results also show that friendly jammer, besides improving the secrecy performance of the system model, also degrades the curves and causes system coding gain losses at high SNR regimes. Results also show that better secrecy performance can be achieved when the relay terminal operates in full-duplex mode.

Impact of the External Co-channel Interferences Over Multiuser Bi-directional Wireless Relaying Networks-Part I: System Description and Outage Analysis

This paper investigates the impact of co-channel interferences (CCIs) caused by the external terminals over multiuser bi-directional amplify-and-forward (AF) relaying. The investigation considers multiuser pair and single bi-directional AF based relay and finite numbers of external interference terminals in the system model. Simultaneous transmission model, which is default mode, creates CCIs that is caused by the other user-pairs (internal terminals) in the system model. The opportunistic source-pair selection (OSPS) strategy achieves near-optimal solution for the internal CCIs challenge and also achieves diversity order in high SNR regimes. However, external terminals’ CCIs are inevitable and degrades the system performance. The main aim of this paper is to clearly state the impacts of external CCIs both for simultaneous and OSPS methods. According to the simulation results, in the case that the external terminals’ transmit powers are identical and non-identical to each other, and if the external terminals’ transmit powers are proportional with SNR, this results on the degradation of the achievable diversity order from

Sum-rate based opportunistic relay selection with channel estimation error for a dual-hop multiple half/full-duplex bi-directional wireless relaying networks

N

Feedback Delay Effects on Physical Layer Security in a Dual-Hop Half/Full-Duplex Bi-Directional Wireless Relaying Networks

N to 0 while also affecting the coding gain. The results also show that, when the external terminals have fixed transmit power values rather than proportional with SNR, in this circumstance, external terminals interference does not affect the achievable diversity order but it affects the system coding gain.The results also show that, when the number of external terminals which affect the user-pairs and relay terminals increase, for both identical and non-identical cases, the losses at the system coding gain exponentially decay. On the other hand, if the external terminals have non-identical transmit powers and if the relay terminal is interfered with more transmit power in comparison with what interferes with the user-pairs, this gives better performance values.

A COMBINED ENCRYPTION AND ERROR CORRECTION SCHEME:AES-TURBO

This paper investigates the opportunistic relay selection method for bi-directional wireless relaying networks. The investigation considers a dual-hop network with a multiple half/full-duplex two-way relay terminal in the system model. The sum-rate based opportunistic relay selection (SR-ORS) strategy selects the best relay terminal based on maximum sum-rate of user-pair and related relay terminal. According to analytical, asymptotic and Monte-Carlo simulation results, the SR-ORS strategy provides better performance results when the relay terminal operates in full-duplex mode.

Multilevel/AES-LDPCC-CPFSK with channel equalization over WSSUS multipath environment

This paper investigates the channel estimation error effects on the opportunistic relay selection strategy. The opportunistic relay selection strategy is based on selecting the maximum sum-rate of half/full-duplex relay terminal among N. The investigation considers a dual-hop multiple half/full-duplex bi-directional wireless relaying networks in the system model. According to Monte-Carlo simulation results, sum-rate based relay selection strategy achieves cooperative diversity in high signal-to-noise regimes both for half/full-duplex cases. However, for the full-duplex based case, if the loop interference variances are relatively high, the achievable cooperative diversity turns out to be 0 from N while also causes system coding gain losses. The CEE causes system coding gain losses in low signal-to-noise ratio regimes. However, in high signal-to-noise ratio regimes, the CEE effects turn out to be at negligible levels.