Physical Layer Carrier Reselection in Multi-Carrier Wireless Systems
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Solution Overview
Problem
In multi-carrier wireless communication systems, the primary carrier carries essential control channels, and existing techniques for changing the primary carrier are slow, leading to potential radio link failures and communication losses, especially when user equipment moves quickly between base station coverage areas.
Innovation Solution
A method is introduced to rapidly change the primary carrier by transmitting a physical layer instruction between network nodes, allowing for fast switching between carriers, which includes determining the need for a carrier change, indicating this change to a third network node, and transmitting a physical layer instruction to reselect a new primary carrier, thereby preventing communication loss.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If radio bearer reconfiguration or RRC signalling is used to change the primary carrier, then the primary carrier can be changed, but the process is slow and may cause communication loss when user equipment moves quickly between base station coverage areas
Solution Approach 1:
The patent segments the carrier change process into two distinct phases: a fast physical layer instruction phase for immediate carrier switching, and a subsequent RRC signalling phase for confirmation and reconfiguration. This segmentation allows the critical speed requirement to be met by the physical layer while maintaining reliability through the subsequent confirmation phase.
Solution Approach 2:
The patent applies preliminary action by sending the physical layer instruction to change the primary carrier before the RRC signalling process is completed. This allows the carrier change to take effect immediately, preventing communication loss, while the subsequent RRC signalling ensures proper reconfiguration and maintains network awareness of the change.
2Reliability
If a physical layer instruction is transmitted to enable fast primary carrier change, then communication continuity is maintained, but the network node must be informed of the change to maintain synchronization
Solution Approach 1:
The patent implements feedback by requiring the network node (eNodeB) to be informed of the primary carrier change through RRC signalling after the physical layer instruction is executed. This feedback mechanism maintains network synchronization and awareness of the carrier change, preventing coordination issues while preserving the benefits of fast switching.
Solution Approach 2:
The patent uses RRC signalling as an intermediary mechanism between the physical layer fast switching and the network control plane. This intermediary ensures that the fast physical layer change is properly communicated to and coordinated with the network node, maintaining system-wide synchronization without compromising the speed of the actual carrier change.
3Reliability
If the primary carrier is changed quickly using physical layer instructions, then radio link failure is prevented, but existing techniques are too slow to respond when user equipment loses radio link connection quickly
Solution Approach 1:
The patent applies preliminary action by enabling the physical layer to send carrier change instructions immediately upon detecting the need for a change, before the slower RRC signalling process completes. This preliminary action at the physical layer ensures that the carrier change happens in time to prevent radio link failure, addressing the time loss issue in existing techniques.
Solution Approach 2:
The patent substitutes the mechanical RRC signalling process with a faster physical layer instruction mechanism for the actual carrier change execution. By replacing the slower higher-layer signalling with a faster physical layer approach for the critical switching action, the system achieves the rapid response needed to prevent radio link failure while maintaining the structured control of RRC signalling for confirmation.
Data Source
AI summary
A method of controlling communication between a first network node and a second network node in a multi-carrier wireless communications system, network nodes and a computer program product are disclosed. The method of controlling communication between a first network node and a second network node in a multicarrier wireless communications system in which a predetermined set of a plurality of carriers are utilized to support communication between the first network node and the second network node, the predetermined set of the plurality of carriers comprising a primary carrier and at least one secondary carrier, comprises the steps of: determining an occurrence of an event requiring a change in the primary carrier; indicating to a third network node that a physical layer instruction is to be transmitted between said first network node and the second network node; and transmitting a physical layer instruction between the first network node and the second network node, the physical layer instruction encoding reselection information to cause the second network node to select a different carrier from the plurality of carriers as a new primary carrier. By sending the instruction using the layer one or physical layer, the speed at which the instruction can be transmitted between the network nodes is vastly increased, which enables fast switching to occur, thereby preventing a loss of communications between the network nodes. By indicating to a third network node that a physical layer instruction is to be transmitted between the first network node and the second network node, maintenance of synchronization is simplified and unpredictable network behavior is minimized.