MAC-hs PDU Header Logic for HS-DSCH in Cell_FACH State
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current 3GPP Release 6 systems limit data rates on FACH channels due to inability to adapt transmission power or modulation and coding schemes, resulting in long call setup times and inefficient use of dedicated channels, especially when UE is in Cell_FACH, Cell_PCH, or URA_PCH states.
Innovation Solution
Modifying MAC architecture to enable use of HS-DSCH in these states by employing UE-specific and cell-specific H-RNTIs, inserting logical channel type and identity in MAC-hs PDU headers, and modifying sub-MAC entities to efficiently identify UEs and channel types, allowing for efficient transmission and reception of common and dedicated logical channels.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If FACH channel is used for downlink transmission, then system compatibility is maintained, but data rate is limited to low values
Solution Approach 1:
The patent introduces HS-DSCH as an intermediary transport channel that bridges the gap between legacy FACH and high-speed data transmission requirements. By mapping logical channels to HS-DSCH when UE is in Cell_FACH state, the system achieves high data rates while maintaining compatibility with existing RRC states and protocols.
2Speed
If dedicated channels are allocated for UE, then high data rates are achieved, but call setup time increases
Solution Approach 1:
The patent enables HS-DSCH transmission in Cell_FACH state before dedicated channels are fully established. By allowing high-speed data transmission on HS-DSCH during the transition period, the system reduces call setup time while maintaining high data rates, as the UE can receive data immediately without waiting for dedicated channel allocation.
3Speed
If HS-DSCH is used in Cell_FACH state, then data rate is improved, but MAC architecture complexity increases
Solution Approach 1:
The patent introduces dynamic state transitions and conditional channel mapping where HS-DSCH can be used in Cell_FACH state under specific conditions. The MAC architecture becomes dynamic by allowing flexible mapping of logical channels to HS-DSCH based on UE state and network configuration, rather than rigid fixed mappings.
Solution Approach 2:
The patent changes the parameter of RRC state definitions by allowing Cell_FACH state to support HS-DSCH transmission, which was traditionally reserved for Cell_DCH state. This parameter change enables high data rates without requiring fundamental architectural restructuring.
4Productivity
If H-RNTI is used for UE identification, then transmission efficiency is improved, but compatibility with legacy UEs decreases
Solution Approach 1:
The patent makes H-RNTI universal by using it for both legacy UEs and HS-DSCH-capable UEs. The same H-RNTI mechanism serves multiple functions: identifying UEs on FACH, identifying UEs on HS-DSCH, and enabling seamless operation across different RRC states, thereby maintaining compatibility while improving efficiency.
Data Source
AI summary
A method and apparatus for transmitting and receiving common logical channel and dedicated logical channel transmissions via a high speed downlink shared channel (HS-DSCH) are disclosed. A medium access control (MAC)-hs entity generates a MAC-hs protocol data unit (PDU) carrying a MAC-c/sh/m PDU and/or a MAC-d PDU. A UE-specific HS-DSCH radio network temporary identifier (H-RNTI) may be used for the MAC-d PDU, and a cell-specific H-RNTI may be used for the MAC-c/sh/b PDU. Alternatively, a cell-specific H-RNTI and one of a cell RNTI (C-RNTI) and a universal terrestrial radio access network RNTI (U-RNTI) may be used in a Cell_FACH state. The logical channel type and identity may be inserted in a MAC-hs PDU header or indicated by a distinct H-RNTI. A logical channel type for common logical channels may be identified in a MAC-c/sh/m PDU header. The logical channel type and identity may be identified by a queue identity.