Logical Channel Mapping to HS-DSCH for WCDMA Resource Efficiency
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Solution Overview
Problem
In WCDMA wireless wide area networks, the static mapping of logical channels onto physical channels results in inefficient use of resources, as S-CCPCH channels consume power and codes that cannot be reused for other traffic, especially in scenarios with few mobile terminals.
Innovation Solution
Mapping logical downlink channels such as CCCH, CTCH, BCCH, MBMS channels, and PCCH onto the High-Speed Downlink Shared Channel (HS-DSCH) instead of FACH and PCH, allowing the omission of the physical S-CCPCH channel and enabling power and code reuse.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If logical channels are statically mapped onto physical channels (PCH, FACH), then channel mapping is simple and reliable, but resource efficiency deteriorates as power and codes cannot be reused for other traffic
Solution Approach 1:
The patent implements dynamic channel mapping where logical channels are no longer statically assigned to physical channels. Instead, the system dynamically selects and maps logical channels (PCCH, CCCH, CTCH, etc.) to the HS-DSCH physical channel based on current network conditions and traffic requirements. This dynamic approach allows the same physical channel resources to be flexibly reused for different logical channels and traffic types, significantly improving power and code efficiency while maintaining reliable communication through adaptive resource allocation.
Solution Approach 2:
The HS-DSCH physical channel is designed to serve multiple functions by carrying various logical channels that were previously dedicated to separate physical channels. The HS-DSCH can dynamically carry PCCH for paging, CCCH for common control, CTCH for traffic, and other logical channels, making a single physical channel universal and multi-functional. This eliminates the need for separate dedicated physical channels for each logical channel type, thereby improving resource efficiency.
2Ease of operation
If separate physical channels (P-CCPCH, S-CCPCH) are used for different logical channels, then channel management is straightforward, but device complexity increases with more channels to manage
Solution Approach 1:
The patent merges multiple separate physical channels (PCH, FACH) into a single unified physical channel (HS-DSCH) that can carry all necessary logical channels. Instead of maintaining separate physical channels for paging, common control, and traffic, the system consolidates these functions onto the HS-DSCH with dynamic mapping. This reduction from multiple physical channels to one unified channel significantly decreases device complexity while the MAC layer maintains efficient management through dynamic channel assignment and identification mechanisms.
3Reliability
If S-CCPCH channel is used for PCH and FACH, then channel coverage is ensured, but transmission speed decreases compared to high-speed channels
Solution Approach 1:
The patent changes the transmission parameters by migrating logical channels from the slower S-CCPCH physical channel to the faster HS-DSCH physical channel. The HS-DSCH supports higher data rates and faster transmission speeds while maintaining reliable coverage through adaptive modulation and coding schemes. This parameter change in the physical layer transmission characteristics enables both high-speed data transfer and reliable channel coverage simultaneously, resolving the speed-coverage tradeoff.
Data Source
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Figure 3
AI summary
According to the invention data in a number of logical downlink channels (PCCH, CCCH, BCCH, CTCH, MCCH, MSCH and MTCH) intended for one or more mobile terminals are received in a first mapping unit (10), where at least a first High Speed Radio Network Temporary identity is allocated to these logical downlink channels addressing a group of mobile terminals for allowing transmission of channel data for reception by mobile terminals. A mobile terminal then reads, from a Broadcast Control Channel, necessary information including a High Speed Radio Network Temporary identity allocated to at least one logical downlink channel, where at least said first identity exists among possible identities. It then listens to a high speed shared control channel for the read identity. In case it detects the identity, the terminal follows a scheduling command, receives data on a high-speed downlink shared channel (HS-DCH) and processes said data.