ETE Framework for QoS guarantee in Heterogeneous Wired-cum-Wireless Networks (cont.) 홍 석 준

R S Access Point /WBM Intermediat e Routers ① RSVP_Path ② Check Available BW in WLAN and whether Outgoing Link supports the request rate. If satisfies, send ③ Otherwise give up reservation ③ RSVP_Resv ④ RSVP_ResvCon f ETE reservation setup procedure (Downlink-Sender is in wired network) After ③, RSVP_ResvConf has not been received after a certain time period. Frees the BW allocated to the flow

R S ETE reservation setup procedure (Uplink-Sender is in wireless network) ① WRESV_REQUES T After ①, AP maps the necessary information in WRESV_REQUEST and sends RSVP_Path to wired receiver After ③, AP (WBM) enforces the admission control, If Successful, AP maps the necessary information in RSVP_Resv and sends WRESV_RESPONSE to wireless sender ② RSVP_Path (RSVP_PathTe ar) ② RSVP_Path (RSVP_PathTe ar) RSVP_Path Err ③ RSVP_Resv (RSVP_ResvT ear) ③ RSVP_Resv (RSVP_ResvT ear) If AP receive Error message, after some time, AP send PathTear message to remove all path states. ④ WRESV_RESPONS E ④ RSVP_ResvConf If flow reservation in the wired network is successful, then AP received RSVP_Resv. Otherwise, AP received RSVP_ResvTear

Optimization (for Uplink flow) R S WRESV_REQUES T WBM checks if the flow can be admitted immediately. If the reservation request cannot be supported in the WLAN, Then it is not necessary to send RSVP_Path to the Receiver.

Support of multicast session 1. All Receivers are in the wired network R R RS (1) Sender is also in the wired network Multicast session can be taken care by RSVP/SBM

Support of multicast session 1. All Receivers are in the wired network R R R S (2) Sender is in the wireless network All reservation request from Receiver are merged at AP The WBM enforces admission control according to merged reservation message Proxy

Support of multicast session 2. All Receivers are in the wireless network (1) Sender is in the wired network R R R S AP records the list of receivers subscribing the same multicast sessions. For each such session, AP only reserves bandwidth (if admitted) for one subscriber. When AP receives data packets from the sender (the multicast session has been reserved successfully), AP simply piggybacks the receiver list in the data packet and broadcasts it.

Support of multicast session 2. All Receivers are in the wireless network (2) Sender is also in the wireless network R R R S This multicast session can be supported efficiently with only one broadcast of each packet from the sender. The list of the receivers should be piggybacked with the broadcast message so that wireless stations that are not in the list will discard the packet.

QoS support of node mobility Home AP Target AP Accept/reject Forward request (with QoS requirment) Forward data MH data Association Send request (with Target AP)

QoS re-negotiation In wireless networks, due to the high channel error rate and node mobility, the link condition may not be very stable, leading to varying available channel bandwidth. In this case, it is possible that the bandwidth requirement of admitted flows can no longer be satisfied. Therefore, QoS re-negotiation is necessary.

when AP notices that available bandwidth decreases to zero, it looks up the flow reservation list, chooses several most recently initiated flows as candidates, and then requests them to handoff. When a MH receives a handoff request, MH follow handoff procedure. QoS re-negotiation

when AP notices that available bandwidth decreases to zero, it looks up the flow reservation list, chooses several most recently initiated flows as candidates, and then requests them to handoff. When a MH receives a handoff request, MH follow handoff procedure. QoS re-negotiation

If handoff succeeds at one MH, AP will be notified and it then tells other MHs to give up handoff. If none of the MHs is able to handoff to neighboring cells, AP will request the sender of the most recently initiated flow to drop the flow. QoS re-negotiation

AP removes the flow under the two situation 1)If the flow sender is in wired network, AP sends a RSVP_ResvTear to the sender to drop the flow in wired nodes 2)If the flow sender is in wireless LAN, AP sends a notification to the corresponding MH, which silently gives up the data transmission of the flow. QoS re-negotiation

In WRESV, the admission control decision is made at the MAC layer, not the network layer. Therefore, message mapping is necessary for correct operations of the protocol. Since the wireless part and wired part are connected at the IP layer, layer interaction only exists between wireless IP layer and IEEE MAC layer in order for both parts to be aware of QoS characteristics of flows to be reserved. Therefore, standing in the center of the functionalities of AP is the cross-layer interaction, i.e., message mapping between IP layer and MAC layer in wireless network. Message mapping at access point

Performance evaluation

Conclusion The proposed integration scheme considers both features of RSVP as well as the characteristic of wireless medium, thereby efficiently supporting multicast session as well as node mobility. With cross-layer interaction, overhead of message mapping at the boundary of the wired and wireless network is significantly reduced.