Low pressure MOCVD has been used to investigate the properties of low temperature buffer layer deposition conditions and their influence on the properties of high temperature GaN epilayers grown subsequently. It is fo...Low pressure MOCVD has been used to investigate the properties of low temperature buffer layer deposition conditions and their influence on the properties of high temperature GaN epilayers grown subsequently. It is found that the surface morphology of the as grown buffer layer after thermal annealing at 1 030 ℃ and 1 050 ℃ depends strongly on the thickness of the buffer layer. In particular when a thick buffer layer is used, large trapezoidal nuclei are formed after annealing.展开更多
Due to the fading property of wireless channels, the instant transmission capability of a fading channel, i.e., the instantaneous channel capacity, will change randomly along time. Usually, a finite size buffer is nee...Due to the fading property of wireless channels, the instant transmission capability of a fading channel, i.e., the instantaneous channel capacity, will change randomly along time. Usually, a finite size buffer is needed at the transmitter to match instant channel capacity with the source data stream. This paper is focused on the queuing process in the buffer. The temporal characteristics of the queueing process in the buffer are investigated, for a buffer-aided communication over block Rayleigh fading channel, in the low signal- to-noise ratio regime. Particularly, the average absorbing time for the buffer to transfer from empty state to overflow sate and from overflow state to empty state, as well as the stable working time in which neither buffer empty nor buffer overflow happens are derived. Theoretical and numerical results show that increasing the buffer size and traffic load properly will improve the efficiency of the transmission.展开更多
文摘Low pressure MOCVD has been used to investigate the properties of low temperature buffer layer deposition conditions and their influence on the properties of high temperature GaN epilayers grown subsequently. It is found that the surface morphology of the as grown buffer layer after thermal annealing at 1 030 ℃ and 1 050 ℃ depends strongly on the thickness of the buffer layer. In particular when a thick buffer layer is used, large trapezoidal nuclei are formed after annealing.
文摘Due to the fading property of wireless channels, the instant transmission capability of a fading channel, i.e., the instantaneous channel capacity, will change randomly along time. Usually, a finite size buffer is needed at the transmitter to match instant channel capacity with the source data stream. This paper is focused on the queuing process in the buffer. The temporal characteristics of the queueing process in the buffer are investigated, for a buffer-aided communication over block Rayleigh fading channel, in the low signal- to-noise ratio regime. Particularly, the average absorbing time for the buffer to transfer from empty state to overflow sate and from overflow state to empty state, as well as the stable working time in which neither buffer empty nor buffer overflow happens are derived. Theoretical and numerical results show that increasing the buffer size and traffic load properly will improve the efficiency of the transmission.
