Flexible HS-DSCH Framing Protocol for HSPA Bitrate and Overhead
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Solution Overview
Problem
Current High Speed Downlink Shared Channel (HS-DSCH) data flow control in wireless communication systems is inefficient due to its inability to handle flexible Radio Link Control (RLC) protocols, leading to limited peak bitrates and increased transport network overhead, especially when dealing with varying packet data unit (PDU) lengths.
Innovation Solution
A new HS-DSCH framing protocol format, referred to as HS-DSCH framing protocol type 2, which allows for the transmission of PDUs of differing lengths by specifying MAC-d PDU credits in octets and supporting larger PDU lengths, enabling flexible PDU lengths and higher bitrates while reducing transport network overhead.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If MAC-d PDU length is increased to achieve higher HSDPA peak bitrate, then bitrate is improved, but coverage is limited
Solution Approach 1:
The data transmission is segmented into multiple MAC-d PDUs of fixed length within a single RLC PDU. This allows the system to use shorter MAC-d PDUs (improving coverage) while still achieving high bitrates through efficient packing of multiple segments in each RLC transmission window, resolving the contradiction between bitrate and coverage
Solution Approach 2:
The patent introduces a new dimension of control by decoupling the RLC PDU length from MAC-d PDU length. Instead of controlling bitrate through MAC-d PDU length alone, the system now controls it through the number of MAC-d PDUs per RLC PDU and the RLC window size, enabling high bitrate with fixed-length shorter MAC-d PDUs that maintain coverage
2Ease of operation
If fixed MAC-d PDU length is used to simplify control, then ease of operation is improved, but flexibility for variable bitrate is reduced
Solution Approach 1:
The patent introduces dynamic control mechanisms where the number of MAC-d PDUs per RLC PDU and the RLC window size can be adjusted based on channel conditions and QoS requirements. This maintains the simplicity of fixed-length MAC-d PDUs while adding flexibility through variable packing density and window size, resolving the contradiction between control simplicity and bitrate flexibility
3Device complexity
If RLC window size is limited to 2047 PDUs, then device complexity is reduced, but productivity is limited
Solution Approach 1:
The patent changes the interpretation of the RLC window size parameter from counting individual MAC-d PDUs to counting RLC PDUs. This allows the same 2047-limit to accommodate much larger amounts of data when each RLC PDU contains multiple MAC-d PDUs, effectively increasing productivity without increasing device complexity or changing the fundamental window management mechanism
Data Source
AI summary
According to an example method performed in a High Speed Downlink Packet Access (HSDPA) environment, a first device generates a High Speed Downlink Shared Channel (HS-DSCH) data frame that includes a plurality of blocks of packet data units. A first block of the plurality of blocks includes packet data units of a first length, and a second block of the plurality of blocks includes packet data units of a different, second length. The first device transfers the HS-DSCH data frame to a second device. The HS-DSCH data frame further includes, for each block of the plurality of blocks, a first information element that indicates a length of the one or more packet data units in the each block, and a second information element that indicates a quantity of packet data units in the each block.