MAC-hs Layer In-Sequence RLC-PDU Delivery for UMTS Processing Delay
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Solution Overview
Problem
In UMTS wireless communication systems, the processing delay in receiving data units over the high speed downlink shared channel is increased due to the sequential reordering requirement of MAC-hs PDUs, which causes unnecessary delays when MAC-d PDUs from different logical channels are not in sequence, leading to waiting for out-of-sequence RLC-PDUs.
Innovation Solution
Providing a subset of information, including the next expected sequence number, to the MAC-hs layer allows it to determine the sequence of RLC-PDUs within MAC-d PDUs, enabling their direct delivery to the RLC entity, thereby reducing processing delay and buffering unnecessary requests for retransmissions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If sequential reordering of MAC-hs PDUs is enforced to ensure in-sequence delivery, then reliability of data transmission is improved, but processing delay increases due to waiting for out-of-sequence packets
Solution Approach 1:
The invention segments the reordering requirement by logical channel, allowing independent processing of in-sequence RLC-PDUs for each logical channel rather than requiring all MAC-d PDUs across all logical channels to be in sequence. This enables partial delivery of in-sequence data while maintaining reliability for delivered portions.
Solution Approach 2:
The MAC-hs layer performs preliminary determination of sequence status for RLC-PDUs before full processing. By checking sequence numbers and identifying in-sequence RLC-PDUs in advance, the system can deliver ready packets immediately without waiting for potentially out-of-sequence packets from other logical channels.
2Reliability
If the MAC-hs layer waits for all RLC-PDUs to be in sequence before processing, then data integrity is maintained, but productivity decreases due to unnecessary waiting
Solution Approach 1:
The processing is segmented by logical channel, allowing the MAC-hs layer to independently identify and deliver in-sequence RLC-PDUs for each logical channel. This maintains data integrity for delivered packets while improving throughput by not blocking on out-of-sequence packets from other channels.
Solution Approach 2:
Instead of waiting for complete in-sequence delivery across all logical channels, the system performs partial action by delivering in-sequence RLC-PDUs as soon as they are identified. This partial delivery approach maintains integrity for delivered data while significantly improving processing throughput.
3Manufacturing precision
If sequential processing of MAC-hs PDUs is enforced, then ordering accuracy is maintained, but processing delay increases due to retransmission waiting
Solution Approach 1:
The MAC-hs layer performs preliminary sequence number checking and identification of in-sequence RLC-PDUs before initiating full processing. This preliminary action enables immediate delivery of in-sequence packets without waiting for retransmission of out-of-sequence packets from other logical channels.
Solution Approach 2:
The invention introduces an intermediary mechanism where the MAC-hs layer acts as a mediator between the physical layer and RLC layer, performing selective sequence verification and forwarding in-sequence RLC-PDUs directly to the RLC layer without requiring complete in-sequence delivery from all logical channels.
Data Source
AI summary
When transmitting medium access control protocol data units for the high speed downlink shared channel over a plurality of hybrid automatic repeat request processes, one of the processes can be in a retransmission procedure. In this case, stalling of the transmission can occur, because the medium access control layer for the high speed downlink shared channel of the receiver apparatus (3) buffers the following packet data units, when a preceding protocol data unit is waiting in the stalled process. To enable an early processing of the already received data, the receiver apparatus determines, whether the next expected service data units for a higher layer such as a radio link control layer, are included in the already received packet data units by taking into account the sequence number for the higher layer. Therefore, the medium access control layer for the high speed downlink shared channel accesses the data of the service data unit for the higher layer.