Joint network-channel coding with C-MRC based demodulate and forward protocol in two-way relay channels C-MRC tabanli kipleme çöz ve i̇let protokolü ile i̇ki yönlü röleli kanallarda birleşik aǧ-kanal kodlamasi

Özdemir, Özgür
Yılmaz, Ali Özgür
Research activities to reduce the system complexity and energy consumption of digital relaying based cooperative wireless networks have yielded the demodulate-forward scheme where the relay performs demodulation, instead of decoding, on the received signals. On the other hand, cooperative maximum ratio combining (C-MRC) is another high-performance low-complexity technique used to combat error propagation in digital relaying without exploiting CRC codes which decreases the transmission efficiency. In this study, we propose a C-MRC based demodulate and forward protocol for two-way relay channels where two users exchange information via a relay. The transmission is divided into three phases in time where the first and second phases are allocated to the transmissions of uncoded or convolutionally encoded data of the users. After demodulation, the relay broadcasts the bit-wise XOR-ed packet to the users in the third phase. The numerical results for Rayleigh fading show that the proposed approach provides full diversity gain.


Concurrent operation of wireless power transfer based contactless slip ring and motor drive system with a single converter
Ayaz, Enes; Keysan, Ozan; Department of Electrical and Electronics Engineering (2022-9)
This thesis presents a novel approach for concurrent power transfer to wired and wireless systems using a single inverter. This proposed approach fits a cost-effective solution to wireless power transfer (WPT) systems used in contactless slip rings (CSR) applications such as sensors, radars, or wind-turbine pitch controls. In conventional systems, there are two separate converters: one is for the motor drive, and the other is for the WPT system. It is proposed that the switching harmonics of the motor drive...
Implementation of stanag 428 hf modem software on tms320c54x digital signal processor
Örümlü, Erhan; Baykal, Buyurman; Department of Electrical and Electronics Engineering (2004)
In this research, STANAG 4285 HF modem software is implemented on TMS320C54x fixed point digital signal processor. The software is optimized in order to meet real-time operation requirements. A fractionally spaced least mean square (LMS) decision feedback equalizer (DFE) is employed for the receiver. In order to improve the convergence of the LMS algorithm a multipass technique is utilized. Based on Watterson̕s model, an HF channel simulator is employed for evaluating the performance of the modem. The simul...
Joint Mitigation of IQ Imbalance and Power Amplifier Impairments by Real Valued Time Delay Neural Networks
Yeşil, Soner; Gürtunca, Burak; Yılmaz, Ali Özgür (2019-08-22)
This paper represents a neural network based joint mitigation of the IQ imbalance and power amplifier nonlinearities that cause degradation in the transmit signal quality of the wireless communication systems. A Real Valued Time Delay Neural Network architecture for this purpose has been verified on a hardware including cascaded NXP-MD8IC925 and NXPBLF8G10LS power amplifier components performing a total of 46dB gain. The test setup has been controlled over MATLAB in order to have a closed loop adaptive digi...
Cooperative relaying schemes for narrow-band frequency hopping wireless ad hoc networks
Yenihayat, Güven; Onat, Furuzan Atay; Kolaǧasioǧlu, Ertuǧrul; Yılmaz, Ali Özgür (2011-08-29)
Cooperative relaying is a promising technique for improving the performance of weak communication links in wireless networks by exploiting spatial diversity induced by relay transmissions. This paper considers cooperative relaying schemes for a narrow- band frequency hopping system. A novel hybrid relaying scheme called opportunistic hybrid relaying, which is specifically designed for this system, is presented. Unlike most relaying schemes in the literature, opportunistic hybrid relaying uses bandwidth effi...
Performance Analysis of Beamforming Techniques in MU-MIMO Systems with Residual RF Impairments
Tamer, Ufuk; SUNU, CANSU; AKTAŞ, EMRE; Yılmaz, Ali Özgür (2015-05-19)
Multiple-input multiple-output wireless communication systems substantially suffer from RF Impairments in the course of the physical implementation of transceivers. In this paper, we study the performance of beamforming techniques in MU-MIMO (Multi-User MIMO) system with one transmitter and two receivers. We showed that the interference cancellation beamforming is suitable in the proposed scenario. In addition, we study the performance of MU-MIMO system with the suitable beamforming technique by taking RF i...
Citation Formats
Ö. Özdemir and A. Ö. Yılmaz, “Joint network-channel coding with C-MRC based demodulate and forward protocol in two-way relay channels C-MRC tabanli kipleme çöz ve i̇let protokolü ile i̇ki yönlü röleli kanallarda birleşik aǧ-kanal kodlamasi,” 2010, Accessed: 00, 2020. [Online]. Available: