JOINT ESTIMATION OF CARRIER FREQUENCY OFFSET AND POWER DELAY PROFILE FOR MIMO-OFDM SYSTEMS

This paper develops a Cyclic Prefix(CP)based joint Maximum-Likelihood(ML)estima-tion algorithm of Carrier Frequency Offset(CFO)and Power Delay Profile(PDP)for Multi-InputMulti-Output Orthogonal Frequency Division Multiplexing(MIMO-OFDM)systems.However,theexact solution of the joint ML estimation is very complex since it needs a search over amulti-dimensional domain.Thus a simplified method is proposed to estimate the CFO and the PDPiteratively via the alternating-projection method which could induce the multidimensional searchproblem to a sequence of simple one-dimensional searches.Simulations show that the proposed algo-rithm is more accurate and robust than the existing algorithms.

A new wide area damping controller design method considering signal transmission delay to damp interarea oscillations in power system

Wide area damping controller(WADC) is usually utilized to damp interarea low frequency oscillation in power system. However, conventional WADC design method neglects the influence of signal transmission delay and damping performance of WADC designed by the conventional method may deteriorate or even has no effect when signal transmission delay is beyond delay margin, an index that denotes delay endurance degree of power system. Therefore, a new design method for WADC under the condition of expected damping factor and required signal transmission delay is presented in this work. An improved delay margin with less conservatism is derived by adopting a new Lyapunov-Krasovskii function and more compact bounding technique on the derivative of Lyapunov-Krasovskii functional. The improved delay margin, which constructs the correlation of damping factor and signal transmission delay, can be used to design WADC. WADC designed by the proposed method can ensure that power system satisfies expected damping factor when WADC input signal is delayed within delay margin. Satisfactory test results demonstrate the effectiveness of the proposed method.

高功放高压联锁电路改进与测试

高压联锁性能的好坏直接影响设备能否正常工作。通过分析CPI高功放(HPA)的延时加高压程序、高压联锁电路和交流延时器工作原理,研究出一种新改进的高压联锁电路方案和用于交流延时器的测试方法。分析阐述表明,该方案和测试方法克服了CPI高功放的高压联锁方案的弊端。另外,根据分析结果设计了延时测试电路,它可对交流延时器性能参数进行定量测试。

Approximate Controllability of Neutral Functional Differential Systems with State-Dependent Delay

This paper deals with the approximate controllability of semilinear neutral functional differential systems with state-dependent delay. The fractional power theory and α-norm are used to discuss the problem so that the obtained results can apply to the systems involving derivatives of spatial variables. By methods of functional analysis and semigroup theory, sufficient conditions of approximate controllability are formulated and proved. Finally, an example is provided to illustrate the applications of the obtained results.

Empirical study on directionalmillimeter-wave propagation in vehicle-to-infrastructure communications between road and roadside

With the increased demand for unmanned driving technology and big-data transmission between vehicles,millimeter-wave(mmWave)technology,due to its characteristics of large bandwidth and low latency,is considered to be the key technology in future vehicular communication systems.Different from traditional cellular communication,the vehicular communication environment has the characteristics of long distance and high moving speed.However,the existing communication channel tests mostly select low-speed and small-range communication scenarios for testing.The test results are insufficient to provide good data support for the existing vehicular communication research;therefore,in this paper,we carry out a large number of channel measurements in mmWave vehicle-toinfrastructure(V2I)long-distance communication scenarios in the 41 GHz band.We study the received signal strength(RSS)in detail and find that the vibration features of RSS can be best modeled by the modified two-path model considering road roughness.Based on the obtained RSS,a novel close-in(CI)model considering the effect of the transmitter(TX)and receiver(RX)antenna heights(CI-TRH model)is developed.As for the channel characteristics,the distribution of the root-mean-square(RMS)delay spread is analyzed.We also extend the twosection exponential power delay profile(PDP)model to a more general form so that the distance-dependent features of the mmWave channel can be better modeled.Furthermore,the variation in both RMS delay spread and PDP shape parameters with TX-RX distance is analyzed.Analysis results show that TX and RX antenna heights have an effect on large-scale fading.Our modified two-path model,CI-TRH model,and two-section exponential PDP model are proved to be effective.

The correlated MIMO channel model for IEEE 802.16n

A more accurate correlated multiple input and multiple output （MIMO） channel model for IEEE 802.16n is presented. On one hand, this MIMO channel model can obtain more precise antenna correlation, which is a key character for MIMO channel and important for the research of IEEE 802.16n and MIMO technologies. On the other hand, it maintains a low complexity of simulation.