Radio link control-acknowledged mode protocol performance modeling in UMTS
ABSTRACT In this paper, we analyze the performance of the RLC (radio link control) layer in acknowledged mode (AM) in UMTS. In a third generation wireless network like UMTS, the RLC-AM protocol is used to transfer data reliably across the radio access network. With an automatic repeat request (ARQ) mechanism, this protocol is able to provide error correction and in-sequence delivery of IP packets. First, we analytically study the behavior of this link layer when reordering is disabled. Then, we present a simple simulation model for in-sequence delivery, easy to implement and able to capture the main characteristics of the RLC protocol. Theoretical and simulation results are compared in order to prove that a very simple simulation model can behave almost exactly like the RLC layer in UMTS.
- [show abstract] [hide abstract]
ABSTRACT: In this paper, in-sequence delivery delay of an acknowledged mode radio link control (AM-RLC) protocol in wideband code division multiple access (W-CDMA) networks is studied. Two special protocol phenomena, duplicated retransmission, and delayed acknowledgment, are reported. A two-step dependent Markov chain is adopted to model the AM-RLC protocol. The in-sequence delivery is evaluated by means of an analysis through tracking the transmission status of a specific packet data unit (PDU) and its blocking PDUs. Analysis results indicate that in-sequence delivery delay is approximately linear with frame error rate. Analysis results also exhibit that in-sequence delivery delay is highly related to status report interval. Based on this observation, a dynamic AM-RLC scheme is proposed. The proposed AM-RLC scheme dynamically changes status report interval according to channel status. Extensive simulations are carried out to verify the effectiveness of the proposed scheme. It is found that the proposed scheme can reduce status report without penalty to in-sequence delivery delay.Wireless Personal Communications 11/2007; 43(4):1209-1227. · 0.43 Impact Factor
Conference Proceeding: Adaptive Packet Combining for IPv6 soft handover applied to Network Mobility[show abstract] [hide abstract]
ABSTRACT: Seamless vertical handover is one of the major challenges toward seamless inter-networking between heterogeneous access networks. To perform seamless vertical handover even under bad radio conditions in network mobility (NEMO) environments, NEMO-SHO has been proposed as an IPv6 soft handover extension that allows packet bicasting via two different wireless links simultaneously. However, the performance gain for TCP traffic was limited because spurious TCP retransmissions were invoked due to the difference of bandwidth and transmission delay between the two links. This paper proposes adding flow control to the packet combining process in NEMO-SHO, which is called adaptive packet combining. Adaptive packet combining estimates packet arrival time from a slow link and delays packets coming from a fast link based on the estimation, which can hide the difference of bandwidth and transmission delay between two links from TCP without any modification on nodes inside a moving network. Adaptive packet combining is thus able to reduce spurious TCP retransmissions. Using 3G and IEEE802.11b link, our experiments show that adaptive packet combining achieves better TCP goodput than Make-Before-Break handover under lossy radio conditions.Personal, Indoor and Mobile Radio Communications, 2008. PIMRC 2008. IEEE 19th International Symposium on; 10/2008
- [show abstract] [hide abstract]
ABSTRACT: The acknowledged mode radio link control (AM-RLC) protocol is one of the most important radio protocols in wideband code division multiple access (WCDMA) and time division-synchronization code division multiple access (TD-SCDMA) mobile communication systems. A modified AM-RLC scheme with adaptive acknowledgement interval is proposed. At the receiver, the acknowledgement interval is dynamically changed according to the channel status. The simulation results show that the proposed AM-RLC scheme outperforms the fixed acknowledgement interval AM-RLC scheme in terms of frame delivery delay and protocol overhead.Frontiers of Electrical and Electronic Engineering in China 01/2009; 4(2):145-148.