Answer Happy

If the values for Rs = 10% symbols/second and b = 3 (i.e., 8-PSK or 8-QAM) are fixed, consider the problem of throughput maximization via adaptive packet length optimization by plotting the throughput n as a function of packet size L for four different received SNR/symbol s2s values in two different fading environments.
-%7C6R, ('=F)--;C!R,C.-E.:(0,19, ) L- bR, L-Cbr (1, L Cross-layer design optimization breaks away from the traditional wireless network design paradigm where each layer of the protocol stack is optimized independently. In this problem, you are asked to consider a cross-layer design framework that judiciously combines adaptive modulation scheme at the physical (PHY) layer, packet length adaptation strategy at the medium access control (MAC) layer, and source rate adaptation at the presentation/application (APP) layer in order to maximize the data link throughput over an additive white Gaussian noise (AWGN) channel as well as fading environments. Assume that the packet length is L bits which include cyclic redundancy check (CRC) bits to ensure bits received in error are detected at the receiver, and K = L-C information bits (payload). The CRC decoder is also assumed to be able to detect all errors in the received packet (since the probability of undetected errors is negligible for reasonable values of C). Suppose that the data link layer provides error robustness by retransmission of erroneously received or lost packets up to a certain maximum number of times (Nmax) as in a truncated selective-repeat automatic repeat request (SR-ARQ) protocol. It can be shown that the truncated SR-ARQ protocol with a specified N max has exactly the same throughput as the no retransmission case (Mpix = 0) and also that of the conventional SR-ARQ protocol with N = 0 (which guarantees the end-to-end delivery of the packet), viz., 1-P n L T where Rs denotes the source data rate (symbols/second), 7 =(1-py***!)/C-P) represents the average number of transmissions per packet, Press = px*** corresponds to the packet loss (or drop) probability at the MAC layer (i.e., packet was not received successfully after max retransmissions), P, -1-[1-Ě. (5,12,)]4is the average packet error probability in a fading environment while 7.(6,12) denotes the average symbol error rate (ASER) of a M-ary modulation with b = log2M bits per symbol at mean received SNR/symbol s2s. In order to maximize the link throughput, the triplet design parameters (i.e., constellation size M = 2, packet length L, and symbol rate Rs which is directly related to the mean SNR/symbol as 12, = {P./N.)/R, where P, denotes the mean received power while n, is the one-sided noise spectral density) should be selected in an adaptive manner. Briefly discuss the advantages and disadvantages of the layered architecture for wireless networks by listing three potential advantages of existing reference models (e.g., OSI, TCP/IP) and three possible drawbacks. In this open-ended course project, you are also asked to investigate the efficacies of adapting various combinations of these optimization variables both individually (i.e., traditional design paradigm) and jointly (i.e., cross-layer design paradigm). Comment on your findings (e.g., difficulties that you have encountered in determining the parameter triplet of optimal joint adaptation for link throughput maximization in multipath fading environments, algorithms/methods employed to overcome those challenges, practical implementation considerations, etc.). 1