tailieunhanh - Vehicular Technologies Increasing Connectivity Part 16

Tham khảo tài liệu 'vehicular technologies increasing connectivity part 16', kỹ thuật - công nghệ, cơ khí - chế tạo máy phục vụ nhu cầu học tập, nghiên cứu và làm việc hiệu quả | Link Budgets How Much Energy is Really Received 441 covariance value is equivalent to maximization of the average received energy or maximization of transmission efficiency. The representative energy gain is the average energy gain of a signal whose energy is uniformly distributed in all the domains Mammela et al. 2010 . Similarly minimization of the covariance value is equivalent to minimization of the average received energy or minimization of transmission efficiency. We demonstrated in Kotelba Mammela 2010b that to maximize the average received energy E Er the instantaneous transmitted energy Et should be proportional to the channel gain G. On the other hand if the instantaneous transmitted energy Et is inversely proportional to the square of the channel gain G then the average received energy E Er is minimized. In general there is some gain for water-filling and some loss for truncated channel inversion compared to the case where the transmitted energy is constant Mammela et al. 2010 . The difference can be several decibels depending on the transmitted signal-to-noise ratio. A good way to include the effect of the covariance in the average link budget is to use the transmitted SNR instead of the received SNR in bit error rate measurements. The transmitted SNR Y is defined to be the ratio of the transmitted energy per bit and the received noise spectral density Mammela et al. 2010 . Fig. 2. Covariance between instantaneous transmitted energy and channel gain for various adaptive power control schemes In the numerical examples in Figs. 3 through 5 we did not use expurgation which implies that the results are valid for power-limited systems. In nonexpurgated systems the analysis is tractable and we are able to illustrate the concepts. In our numerical results shown in Figs. 2 and 3 we used a composite gamma lognormal fading channel model Simon Alouini 2000 pp. 24-25 with multipath fading parameter m 4 shadowing channel gain Ị 442 Vehicular Technologies Increasing

TỪ KHÓA LIÊN QUAN
crossorigin="anonymous">
Đã phát hiện trình chặn quảng cáo AdBlock
Trang web này phụ thuộc vào doanh thu từ số lần hiển thị quảng cáo để tồn tại. Vui lòng tắt trình chặn quảng cáo của bạn hoặc tạm dừng tính năng chặn quảng cáo cho trang web này.