Key Laboratory of Broadband Wireless Communications and Sensor Network Technology

Nanjing, China

Key Laboratory of Broadband Wireless Communications and Sensor Network Technology

Nanjing, China
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Wang Y.,Nanjing University of Posts and Telecommunications | Wang Y.,Key Laboratory of Broadband Wireless Communications and Sensor Network Technology | Yang L.,Nanjing University of Posts and Telecommunications | Yang L.,Key Laboratory of Broadband Wireless Communications and Sensor Network Technology | And 2 more authors.
2011 IEEE 3rd International Conference on Communication Software and Networks, ICCSN 2011 | Year: 2011

This context addresses the subcarrier and power allocation problem in the uplink of an OFDMA system under the cognitive radio environment. The objective is to maximize the sum transmission rate of secondary users, without causing adverse interference to the primary users. We formulate the optimization problem subject to the individual power constraints and the interference constraints. We also propose two suboptimal power loading algorithms that are less complex and a new subcarrier allocation algorithm. The performance of the optimal scheme is compared with the performance of the suboptimal. Simulation results show that the optimal algorithm significantly improves the sum transmission rate, and provides good convergence. © 2011 IEEE.


Zhi H.,Nanjing University of Posts and Telecommunications | Zhi H.,Key Laboratory of Broadband Wireless Communications and Sensor Network Technology | Yang L.,Nanjing University of Posts and Telecommunications | Yang L.,Key Laboratory of Broadband Wireless Communications and Sensor Network Technology | And 2 more authors.
Wireless Personal Communications | Year: 2013

The outage probability and ergodic capacity analysis for decode-and-forward two-way relaying system is investigated in this paper. First, the exact expressions (or bounds) of outage probability, ergodic capacity and average bidirectional ergodic capacity (ABEC) for max-min relay selection, random relay selection and direct transmission protocols are derived through theoretic analysis, and performance comparisons among different relay selection protocols are developed. Then a novel maximum average bidirectional mutual information (MABM) relay selection protocol is proposed and analyzed. Simulation results demonstrate that the derived analytical results fit well with Monte-Carlo simulations. The proposed MABM protocol can always achieve larger ABEC than other protocols while keeping low outage probability, and the MABM and max-min protocols in this paper can always achieve better performance than the max-min selection and max-sum selection in Krikidis (IEEE Trans Veh Technol 59(9):4620-4628, 2010). In addition, outage probability, ergodic capacity and ABEC performance of the proposed protocol become worse while distance becomes larger. © 2013 Springer Science+Business Media New York.


Zhi H.,Nanjing University of Posts and Telecommunications | Zhi H.,Key Laboratory of Broadband Wireless Communications and Sensor Network Technology | Yang L.,Nanjing University of Posts and Telecommunications | Yang L.,Key Laboratory of Broadband Wireless Communications and Sensor Network Technology | And 2 more authors.
Wireless Personal Communications | Year: 2013

Two novel best-relay selection protocols, the jointing adaptive modulation max-min (AM-MM) protocol and the jointing adaptive modulation maximum harmonic mean (AM-MHM) protocol, are proposed for two-way opportunistic relaying systems with amplify-and-forward policy (TWOR-AF). By integrating the adaptive modulation with the conventional max-min (NonAM-MM) and maximum harmonic mean protocols, the effect of the modulation schemes used at both sources is exploited perfectly in the proposed AM-MM and AM-MHM protocols. The analytical expressions to the approximate upper bounds of overall average symbol error probability (SEP) for TWOR-AF systems with these different relay selection protocols are obtained through theoretic analysis. The numerical results demonstrate that the average SEP of TWOR-AF systems can be improved greatly when the proposed jointing adaptive modulation relay selection protocols are performed. Furthermore, in certain channel realizations, the adaptive modulation non-selection protocol outperforms the conventional NonAM-MM protocol in which the adaptive modulation is not integrated. © 2012 Springer Science+Business Media New York.


Zhang X.,Nanjing University of Posts and Telecommunications | Zhang X.,Key Laboratory of Broadband Wireless Communications and Sensor Network Technology | Yang L.-X.,Nanjing University of Posts and Telecommunications | Yang L.-X.,Key Laboratory of Broadband Wireless Communications and Sensor Network Technology | And 2 more authors.
International Conference on Communication Technology Proceedings, ICCT | Year: 2011

Coordinated multi-point transmission/reception (CoMP), in which base stations cooperation during the downlink, has been considered as a attractive way of achieving higher performance and mitigating interference, especially for terminals at cell edges. In this paper, distributed precoding for multicell-MISO downlink CoMP is considered. Most previous work in the area is on the assumption that base stations have knowledge of both data symbols and full channel state information (CSI), which leads to heavy exchange of channel state information and signal information over backhaul links. In this paper, several distributed precoding strategies (Distributed MRT, distributed ZF, distributed LVSINR and DVSINR) for multicell-MISO downlink CoMP are analyzed, which supposes that each base station only has local CSI and the precoders can be devised at each BS in a distributed manner, and Monte Carlo simulations demonstrate the performance of such strategies. © 2011 IEEE.


Wang L.,Key Laboratory of Broadband Wireless Communications and Sensor Network Technology | Wang L.,Nanjing Southeast University | Xue H.,Key Laboratory of Broadband Wireless Communications and Sensor Network Technology | Jiang G.,Key Laboratory of Broadband Wireless Communications and Sensor Network Technology | And 2 more authors.
2014 6th International Conference on Wireless Communications and Signal Processing, WCSP 2014 | Year: 2014

The existing spectrum sensing schemes based on free probability theory (FPT) have a high sensing performance especially in cases of low signal to noise ratio (SNR) and a small number of samples. However they all based on data fusion rule when performing cooperative spectrum sensing. The secondary users (SUs), in this case, have to transmit large amounts of sensing data to a fusion center (FC). It may cause the FC overloaded, which is considered as an extreme challenge to the practical application. In this paper, a new cooperative FPT-based spectrum sensing scheme is proposed, which utilizes the OR decision fusion rule to overcome the aforementioned shortcomings of such an algorithm. Simulation results over MIMO rayleigh fading channel demonstrate that, with decision fusion, the performance of our proposed scheme is much higher than that of the eigenvalue-based detector, even though the latter uses data fusion rule. Therefore, the proposed scheme is more effective and practical on the overall performance. © 2014 IEEE.


Wang L.,Key Laboratory of Broadband Wireless Communications and Sensor Network Technology | Wang L.,Nanjing Southeast University | Xue H.,Key Laboratory of Broadband Wireless Communications and Sensor Network Technology | Jiang G.,Key Laboratory of Broadband Wireless Communications and Sensor Network Technology | And 2 more authors.
2014 6th International Conference on Wireless Communications and Signal Processing, WCSP 2014 | Year: 2014

In the practical application of cognitive radio network, it is especially important to improve the energy efficiency for those energy-constrained cognitive users. From the perspective of maximizing the energy efficiency in cognitive radio networks, this paper considers the case that the sudden appearance of the primary user can lead to data collision when the cognitive user is transmitting data. Then the optimization mathematical model of energy efficiency is given by using frame period and sensing time. The optimization problem is analyzed theoretically and verified by computer simulations. The theoretical analysis and computer simulation results show that the energy efficiency firstly increases and then decreases with the increase of the sensing time as well as the frame period, and there is an optimal combination of optimal sensing time and frame period to maximize the energy efficiency. © 2014 IEEE.

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