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AD HOC NETWORKS Technologies and Protocols phần 3

Giải pháp của bạn phải yêu cầu số tiền tối thiểu của nỗ lực hành chính. Trong đó hai hành động bạn nên thực hiện? (Mỗi câu trả lời chính xác trình bày một phần của giải pháp. Chọn hai) A. Thiết lập lại các tài khoản máy tính cho File1 trong Active Directory Users and Computers. B. Thiết lập lại mật khẩu cho | Performance of collision avoidance protocols 35 the modified formula for throughput is simply Th 1 jldata ttsl f ttw 3 lifts 3 lets 3 Idata 3 lack 3 4t 1 3 tTs 3- lifts lets 3 2r l 7T J 7TS 3 lifts 3- lets 3 Idata 3 3t 3tTs 1.6 When the deviatory factor ị3 equals zero Equation 1.6 is reduced to Equation 1.5 . 2.1.2 Numerical Results In this section we compare the throughput of the RTS CTS scheme with a non-persistent CSMA protocol in which there is a separate channel over which acknowledgments are sent in zero time and without collisions. The performance of the latter protocol in multi-hop networks has been analyzed by Wu and Varshney 9 and we should note that in practice the performance of the CSMA protocol would be worse as both data packets and acknowledgments are transmitted in the same channel. We present results when either relatively large data packets or relatively small data packets are sent. Let T denote the duration of one time slot. RTS CTS and ACK packets last 5-r. As to the size of data packets we consider two cases. One case corresponds to a data packet that is much larger than the aggregate size of RTS CTS and ACK packets. The other case corresponds to a data packet being only slightly larger than the aggregate size of RTS CTS and ACK packets. In the latter case which models networks in which radios have long turn-around times and data packets are short it is doubtful whether a collision avoidance scheme should be employed at all because it represents excessive overhead. We first calculate throughput with different values of a which we define as the ratio between the circular region including nodes affected by an RTS CTS handshake and the largest possible circular region in which nodes are guaranteed to be connected with one another. We find that though the relationship between the ready probability p and transmission-attempt probability p under different values of a might be somewhat different the throughput is largely unaffected by a which is .