Cooperative localization for next-generation converged networks with closed-form solution

In this article, a novel cooperative wireless localization scheme based on information fusion is proposed. The scheme combines large-scale arrival time and small-scale distance measurements obtained from the next-generation converged networks. The maximum likelihood （ML） estimate of the terminal＇s position is derived with closed-form solution, and the Cramer-Rao lower bound （CRLB） of the estimate error is investigated. Both theoretical analysis and simulation results verify that the proposed localization scheme can significantly enhance the location precision. Moreover, the mean square error of position estimate approximates the CRLB when the number of reference stations increases, which indicates that the proposed ML estimator is asymptotically efficient.

SER bound for ordered ZF-SIC receiver in M-QAM MIMO system

With the advances of the 4th generation （4G） mobile communications targeting multi-user QoS-guaranteed multimedia services, multiple input multiple output （MIMO） combined with multi-level quadrature amplitude modulation （M-QAM） technique gains great popularity for its capability of supporting high data rate. In this article, the statistical distribution of signal to noise plus interference ratio （SINR） in each recursive step of optimal ordered zero-forcing perfect successive interference cancellation （ZF-OOPSIC） detection is deduced based on order statistics theory. The symbol error rate （SER） of M-QAM MIMO system with ZF-OOPSIC detector is analyzed under fiat Rayleigh fading channel. This precise analytical SER result could be taken as the lower bound of various zero-forcing ordered successive interference cancellation （ZF-OSIC） receivers. Combining the analytical SER expression for linear zero-forcing （ZF） receiver as upper bound, the rough range of SER for various ZF-OSIC detectors could be obtained. Monte Carlo （MC） simulations validate the analytical results and prove the conclusions.

Effective resource scheduling scheme considering scheduling relevancy for downlink joint transmission system

Coordinated multi-point （CoMP） transmission is a promising technique to improve both cell average and cell edge throughput for long term evolution-advanced （LTE-A）. For CoMP joint transmission （CoMP-JT） in heterogeneous scenario, if joint transmission （JT） users are firstly scheduled, other non-JT users will not be allocated sufficient resources, i.e., scheduling relevancy exists in the users under different cells in the same coordination cluster. However, the CoMP system throughput will decline remarkably, if the impact of scheduling relevancy is not considered. To address this issue, this paper proposes a novel scheduling scheme for CoMP in heterogeneous scenario. The principles of the proposed scheme include two aspects. Firstly, this scheme gives priority to user fairness, based on an extended proportional fairness （PF） scheduling algorithm. Secondly, the throughput of the coordination cluster should be maintained at a high level. By taking the non-CoMP system as a baseline, the proposed scheme is evaluated by comparing to random PF （RPF） and orthogonal PF （OPF） scheme. System-level simulation results indicate that, the proposed scheme can achieve considerable performance gain in both cell average and cell edge throughput.

Space time frequency coding for dual polarization MIMO in hybrid mobile satellite system

The hybrid mobile satellite system operating in a single frequency network （SFN） mode is increasingly becoming attractive. The combination of satellite component （SC） and terrestrial component （TC） promises a better quality of service （QoS）. Multimedia broadcast and multicast services （MBMS） are expected to be prevailed in this kind of system. Several space frequency （SF） or space time （ST） codes have been proposed to enhance the system performance due to the lack of reverse link and omni-directional transmission. However, they mostly consider the system with only one SC and one TC and fail to make full use of available diversities. This paper presents a novel way to realize the dual polarization multiple input multiple output （MIMO） transmission by using the space time frequency （STF） code. The theoretical analysis and simulations indicate that the application of STF code can improve the system performance dramatically. A higher diversity gain can be achieved due to the cooperative transmission of SC and TC, while the coding gain can be enhanced by the reusing of STF code between SCs or TCs. Even if some of the links are lost, it can still work properly and benefit from the STF code. The relative relay can result in a degradation up to 0.5 dB in the coding gain.

Optimal energy-efficient scheme for two-way relay channel using physical layer network coding

Systems are always designed and optimized based on full traffic load in the current literatures. However, practical systems are seldom operating at full load, even at peak traffic hours. Instead of maximizing system rate to achieve the full load, an optimal energy-efficient scheme to minimize the transmit power with required rates is investigated in this article. The considered scenario is a two-way relay channel using amplify-and-forward protocol of physical layer network coding, where two end nodes exchange messages via multiple relay nodes within two timeslots. A joint power allocation and relay selection scheme is designed to achieve the minimum transmit power. Through convex optimization theory, we firstly prove that single relay selection scheme is the most energy-efficient way for physical layer network coding. The closed-form expressions of power allocation are also given. Numerical simulations demonstrate the performance of the designed scheme as well as the comparison among different schemes.