7.3.5 Details of MAC-es

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For each UE, there is one MAC-es entity in the SRNC. The MAC-es sublayer handles E-DCH specific functionality, which is not covered in the MAC-e entity in Node B. In the model below, the MAC-es comprises the following entities:

– Reordering Queue Distribution:
The reordering queue distribution function routes the MAC-es PDUs to the correct reordering buffer based on the SRNC configuration.

– Reordering:
This function reorders received MAC-es PDUs according to the received TSN and for FDD Node-B tagging i.e. CFN, subframe number. MAC-es PDUs with consecutive TSNs are delivered to the disassembly function upon reception. Mechanisms for reordering mac-es PDUs are left to the implementation. The number of reordering entities is controlled by the SRNC. There is one Reordering Queue per logical channel.

– Macro diversity selection (FDD only):
The function is performed in the MAC-es, in case of soft handover with multiple Node-Bs (The soft combining for all the cells of a Node-B takes place in the Node-B). This means that the reordering function receives MAC-es PDUs from each Node-B in the E-DCH active set. The exact implementation is not specified. However the model below is based on one Reordering Queue Distribution entity receiving all the MAC-d flow from all the Node-Bs, and one MAC-es entity per UE.

– Disassembly:
The disassembly function is responsible for disassembly of MAC-es PDUs. When a MAC-es PDU is disassembled the MAC-es header is removed, the MAC-d PDU’s are extracted and delivered to MAC-d.

Figure 7.3.5-1: UTRAN side MAC architecture / MAC-es details (SHO case, FDD only)

Figure 7.3.5-2: UTRAN side MAC architecture / MAC-es details (TDD only)