Performance Study of Link Layer and MAC Layer Protocols to Support TCP in 3G CDMA Systems
IEEE Transactions on Mobile Computing
Joint Reliability of Medium Access Control and Radio Link Protocol in 3G CDMA Systems
IEEE Transactions on Computers
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In the wireless data systems, automatic repeatrequest (ARQ) is used in order to reliably deliver packets to the upper layer while hybrid ARQ (HARQ) intends to improve the reliability over the air through the combination with other transmission techniques, e.g., modulation and channel coding. While the two functions are complementary to each other, it has been typically recognized as if they work independently at their corresponding layer. However, we note that the retransmission via ARQ is correlated with whether HARQ eventually delivers a packet successfully within a retransmission limit. Capturing this observation, we in this paper introduce a new ARQ feedback scheme called Cross-Layer ARQ (CL-ARQ). CL-ARQ makes use of the acknowledgement of HARQ internally. CL-ARQ not only allows ARQ to operate without explicit acknowledgement, but also improves the reliability combined with existing ARQ protocols. Especially, when the entities in charge of HARQ and ARQ are located far apart geographically, we show that CL-ARQ remarkably outperforms other schemes. Additionally, CL-ARQ is shown to resolve the stall problem, which occurs when the link capacity can not be fully utilized due to the limitation of ARQ window size. We evaluate the performance of CL-ARQ via both analysis and simulations.