Tham khảo tài liệu 'quality of service and resource allocation in wimaxfig part 16', kỹ thuật - công nghệ, cơ khí - chế tạo máy phục vụ nhu cầu học tập, nghiên cứu và làm việc hiệu quả | 366 Quality of Service and Resource Allocation in WiMAX 4. Relay networking architecture options This section lists several options for modifying the WiMAX architecture to enable support for relay. Each option is presented and its main cons and pros are listed. It begins with a discussion regarding MAC-based relay as suggested by and then proceeds to network-based relay. MAC-based relay The first architecture option to consider is called MAC-based relay . MAC-based relay is the approach used by non-transparent mode. In this approach the backhaul link between the Relay Station RS and the Multi-hop Relay Base Station MRBS is contained within the MAC L2 layer. In most aspects the ASN-GW is unaware of the fact that a MS is connected to the BS via a RS. Rather the MRBS behaves as if the MS is registered with it directly. In this approach no networking modifications are required to support relay traffic though some modifications may be needed for RRM and other aspects see below . From a networking perspective the RS does not behave like a BS. The GRE tunnel used to carry the Service Flow is terminated at the MRBS and not at the RS. MAC-based relay can support multi-hop 3-hop and more relay without network modifications. Pros No network modifications. Lower latency for relay transport Easier to implement QoS constraints because RS-MRBS link uses dedicated MAC which can contain more information than available over R6. Cons RS-MRBS link not compliant to MAC RS functionality does not build over existing WiMAX capabilities. Mobility RRM needs to be modified to support relay. Network-based relay The MAC-based relay has one important drawback The air interface between the RS and the MRBS in not compliant. While modifying an existing BS networking capabilities is relatively painless modifying as existing BS to support new MAC features such as is much more complex. Likewise upgrading a deployed network to .
