In this paper, we propose Transmission Control Protocol (TCP)-aware cross layer scheduling algorithms in a multipoint-to-point network such as the uplink of an IEEE 802.16 (WiMAX) network. Inadequate bandwidth allocation to a TCP flow may lead to timeout and since TCP source drops its congestion window ( @math ) immediately after a timeout, it may affect the average throughput adversely. On the other hand, since the TCP source increases its @math only linearly upon the availability of bandwidth, any excess assignment of bandwidth may remain underutilized. The proposed scheduling algorithms address this by allocating the resources based on @math and TCP timeout. Moreover, since we focus on uplink scheduling, we consider that only flow level resource requirement is communicated to the Base Station ( @math ) instead of per packet information. The schedulers also take into account the wireless channel characteristics and are thus cross layer in nature. Through exhaustive simulations, we demonstrate that the proposed schedulers exhibit enhanced throughput and fairness properties when compared to that of Round Robin (RR) scheduler under different shadowing. We demonstrate a gain between 3.5 to 15 in throughput and 15 to 25 in channel utilization over RR scheduler under different shadowing.
In @cite_19 , the authors have illustrated the performance of TCP and UDP based applications through rigorous experiments conducted in an IEEE 802.16 deployed network as well as in test-beds. It has been observed that TCP applications suffer significantly as compared to UDP applications if the scheduling scheme does not consider the nature of TCP (TCP parameters). This key observation has encouraged us to work on scheduling schemes which are TCP-aware.
@cite_19
2119994812
In this paper, we focus on various experiments conducted to analyze the performance of Transmission Control Protocol (TCP) and Universal Datagram Protocol (UDP) based applications in a IEEE 802.16 deployed network. We analyze the effect of Medium Access Control (MAC) and Physical layer characteristics on the performance of TCP and UDP-based applications. Our key findings are: (i) throughput achieved by TCP-based applications is lower than that of UDP-based applications, (ii) slot utilization of TCP-based applications is lower than that of UDP-based applications and (iii) throughput of TCP-based applications suffers in the presence of UDP-based applications for similar channel states. We also observe that throughput achieved by both TCP and UDP-based applications with Automatic Repeat ReQuest (ARQ) set in system are higher as compared to that of without ARQ. The findings of these experiments can be adopted while designing efficient scheduling schemes for IEEE 802.16-based network, such that higher throughput, utilization and better delay performance can be achieved.