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Limitations in the Code Acquisition Performance for Adaptive Filter Versus Correlator
Takki Yu,Changeon Kang,Daesik Hong IEEE Signal Processing Society 2006 IEEE signal processing letters Vol.13 No.11
<P>In this letter, we compare the code acquisition performance of the adaptive filter to that of the correlator in direct sequence spread spectrum (DS/SS) systems. The test variables used in the code acquisition are statistically analyzed for both schemes, and then, the obtained results are used in comparing the detection and false-alarm probabilities. Analysis and simulation results show that the correlator outperforms the adaptive filter under most acquisition environments</P>
주파수 영역에서의 간단한 zero-forcing 기법을 이용한 속도 적응형 채널 추정 기법
류탁기,박구현,홍대식,강창언,Yu Takki,Park Goohyun,Hong Daesik,Kang Changeon 한국통신학회 2006 韓國通信學會論文誌 Vol.31 No.1a
본 논문에서는 주파수 영역에서의 간단한 zero-forcing 기법을 이용한 속도 적응형 채널 추정 기법을 제안한다. 제안된 기법은 최적의 채널 추정 기법인 Wiener 필터의 주파수 응답을 구형(rectangular)으로 근사화하여 유도된다. 채널 추정 과정은 수신 신호에서 최대 도플러 주파수보다 큰 주파수 성분들을 제거함으로써 수행된다. 제안된 기법은 채널 계수와 이동체 속도에 대한 동시 추정 기법으로 확장 가능하며, 하나의 FFT 구조를 사용하여 효과적으로 구현 가능하다. 실험 결과를 통해 제안된 채널 추정 기법은 기존의 속도 적응형 채널 추정 기법들보다 넓은 속도 범위에서 낮은 채널 추정 MSE 성능을 보여주며, 확장된 동시 추정 기법은 다양한 채널 환경에서 안정된 추정 성능을 보인다. 마지막으로 제안된 기법에 대한 MSE 성능이 수식적으로 유도된다. In this paper, we propose a velocity-adaptive channel estimation scheme using the simple zero-forcing technique in the frequency domain. Channel estimation is performed by removing frequency components that are higher than the maximum Doppler frequency in the received signal. The proposed scheme can be extended to the combined estimation scheme for channel coefficients and mobile velocity using one FFT/IFFT module. Simulation results show that the proposed scheme outperforms conventional schemes for a wide range of mobile velocities($3{\sim}300\;Km/h$). Finally, the MSE for the proposed channel estimation scheme is analyzed.
Statistically Controlled Opportunistic Resource Block Sharing for Femto Cell Networks
Shin, Dae Kyu,Choi, Wan,Yu, Takki The Korea Institute of Information and Commucation 2013 Journal of communications and networks Vol.15 No.5
In this paper, we propose an efficient interference management technique which controls the number of resource blocks (or subcarriers) shared with other cells based on statistical interference levels among cells. The proposed technique tries to maximize average throughput of a femto cell user under a constraint on non-real time control of a femto cell network while guaranteeing a target throughput value of a macro cell user. In our proposed scheme, femto cells opportunistically use resource blocks allocated to other cells if the required average user throughput is not attained with the primarily allocated resource blocks. The proposed method is similar to the underlay approach in cognitive radio systems, but resource block sharing among cells is statistically controlled. For the statistical control, a femto cell sever constructs a table storing average mutual interference among cells and periodically updates the table. This statistical approach fully satisfies the constraint of non-real time control for femto cell networks. Our simulation results show that the proposed scheme achieves higher average femto user throughput than conventional frequency reuse schemes for time varying number of users.