  In traditional communication system, information of APP (Application) layer,
transport layer and MAC (Media Access Control)layer has not been fully
interacted,which inevitably leads to inconsistencies among TCP congestion
state, clients'requirements and resource allocation. To solve the problem, we
propose a joint optimization framework, which consists of APP layer, transport
layer and MAC layer, to improve the video clients'playback experience and
system throughput. First, a client requirement aware autonomous packet drop
strategy, based on packet importance, channel condition and playback status, is
developed to decrease the network load and the probability of rebuffering
events. Further, TCP (Transmission Control Protocol) state aware downlink and
uplink resource allocation schemes are proposed to achieve smooth video
transmission and steady ACK (Acknowledgement) feedback respectively. For
downlink scheme, maximum transmission capacity requirement for each client is
calculated based on feedback ACK information from transport layer to avoid
allocating excessive resource to the client, whose ACK feedback is blocked due
to bad uplink channel condition. For uplink scheme, information of RTO
(Retransmission Timeout) and TCP congestion window are utilized to indicate ACK
scheduling priority. The simulation results show that our algorithm can
signficantly improve the system throughput and the clients'playback continuity
with acceptable video quality.
