Soft Cell Uplink Prioritization via Logical Channel Mapping
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Solution Overview
Problem
In LTE wireless communication systems, there is a lack of control over which link a logical channel is mapped to, either the macro node (anchor link) or the pico node (booster link), due to latency limitations in the backhaul network, making it difficult for the wireless device to transmit information directly to the appropriate node.
Innovation Solution
The wireless device obtains information on which link one or more logical channels are mapped, allowing it to select and map the logical channels to either the macro or pico node, using new RRC signaling or existing MAC/L1/L2 signaling, with attributes like 'anchor only', 'booster only', or 'any' to determine the mapping.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the wireless device transmits information to both macro node and pico node without link mapping control, then the system provides heterogeneous network coverage and capacity, but the backhaul network latency causes information delivery delays and inefficiency
Solution Approach 1:
The patent segments the uplink transmission by dividing logical channels into different groups (first set and second set) and mapping them to different links (macro node and pico node respectively). This segmentation allows direct transmission of certain information to the appropriate node without backhaul forwarding, thereby reducing latency and improving delivery efficiency.
Solution Approach 2:
The patent introduces link mapping information as an intermediary mechanism that guides the wireless device to select the appropriate link for transmission. This mapping information acts as a mediator between the wireless device and the network nodes, enabling direct routing of information to the correct node and eliminating the need for backhaul network forwarding in many cases.
2Reliability
If the pico node transmits full set of common signals and channels as a traditional cell, then the cell provides complete cell functionality, but the energy consumption increases and interference is reduced only partially
Solution Approach 1:
The patent extracts the essential cell functionality (common signals and channels) from the pico node by maintaining them at the macro node. The pico node only needs to provide data transmission capacity, while the macro node continues to provide the full set of common signals. This extraction reduces pico node energy consumption while maintaining complete cell functionality through the macro node's common signals.
Solution Approach 2:
The macro node assumes a universal role by providing both the full set of common signals and channels and serving as the primary control node. This multi-functionality allows the system to maintain complete cell functionality without requiring the pico node to duplicate all cell functions, thereby reducing pico node energy consumption.
3Productivity
If the wireless device can select and map logical channels to specific links, then the information is transmitted directly to the correct node reducing backhaul dependency, but the device complexity increases due to mapping control requirements
Solution Approach 1:
The patent applies preliminary action by pre-configuring link mapping information in the wireless device through higher layer signaling (RRC or MAC/L1/L2). This pre-configuration allows the device to automatically select the appropriate link based on pre-stored mapping rules without complex real-time decision-making, thereby reducing device complexity while enabling direct transmission capability.
4Reliability
If the soft cell approach is implemented without logical channel mapping control, then the system achieves mobility robustness and energy efficiency, but the interference management is less effective due to uncontrolled uplink transmissions
Solution Approach 1:
The patent segments uplink transmissions by directing different logical channels to different links based on pre-configured mapping information. This segmentation allows the network to control which transmissions occur on which link, enabling effective interference management while maintaining the mobility robustness and energy efficiency benefits of the soft cell approach.
Data Source
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AI summary
The invention relates to a method in a wireless device for mapping a logical channel to one of a first and a second link. The first link is maintained to a first radio network node and the second link is maintained to a second radio network node. The method comprises obtaining (910) information indicating to which of the first and the second links one or more of at least one logical channel is mapped. The method also comprises selecting (920) a logical channel among the at least one logical channel, and mapping (930) the selected logical channel to one of the first and the second links based on the obtained information. The invention also relates to a corresponding method in the first radio network node.