Radio Coexistence Gap Pattern Configuration for LTE Interference Mitigation
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Solution Overview
Problem
Conventional LTE systems face coexistence issues due to interference between LTE radios and other radio technologies like Bluetooth and WLAN, particularly in the Industrial Scientific and Medical (ISM) band, leading to unacceptable error rates and disruption in voice services, as the eNodeB is not adequately aware of interference on the UE side, resulting in unresolved uplink coexistence issues.
Innovation Solution
A method and apparatus for determining and selecting gap pattern configurations that meet scheduling timeline constraints of LTE, reducing conflicts with other radio access technologies, allowing for autonomous channel or RAT changes by the UE to mitigate interference, and informing the eNodeB of coexistence issues to facilitate coordinated solutions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If LTE radio operates simultaneously with Bluetooth and WLAN radios, then multi-radio functionality is provided, but interference occurs between radios causing unacceptable error rates and service disruption
Solution Approach 1:
The patent implements Time Division Multiplexing (TDM) where different radios operate in periodic time slots. The LTE radio transmits during specific time intervals while Bluetooth and WLAN radios are muted, then roles are swapped in subsequent intervals. This periodic time-division approach allows all radios to function while preventing simultaneous interference, thus maintaining both multi-radio versatility and acceptable error rates.
2Productivity
If LTE uplink channel operates in ISM band, then spectrum utilization is improved, but interference with Bluetooth and WLAN channels occurs
Solution Approach 1:
The patent employs periodic time-division multiplexing where the LTE uplink channel alternates between transmitting and muting in scheduled intervals. During LTE transmit intervals, Bluetooth and WLAN are muted; during LTE mute intervals, Bluetooth and WLAN can transmit. This periodic action allows LTE to utilize the ISM band effectively while periodically yielding the channel to prevent harmful interference with other radios.
3Productivity
If eNodeB makes handover decisions based on RSRP reports, then network optimization is achieved, but ping-pong effect occurs between corrupted and desired channels
Solution Approach 1:
The patent introduces a new feedback mechanism where the UE measures and reports Reference Signal Received Quality (RSRQ) in addition to RSRP. The eNodeB uses this quality-based feedback to distinguish between good and corrupted channels, preventing handovers to channels that would cause coexistence issues. This enhanced feedback loop maintains network optimization while ensuring channel stability by avoiding ping-pong effects between corrupted and desired channels.
4Reliability
If UE autonomously changes channel or RAT, then coexistence issues are mitigated, but coordination with eNodeB is reduced
Solution Approach 1:
The patent implements a preliminary coordination mechanism where the UE reports coexistence issues and candidate channels to the eNodeB before executing channel changes. The eNodeB provides approval or alternative suggestions based on network state. This preliminary action allows the UE to proactively manage coexistence while maintaining necessary coordination, reducing the need for complex real-time negotiation during actual channel transitions.
Data Source
AI summary
To improve performance in devices capable of communication using multiple radio access technologies (RATs), a gap pattern may be constructed in which a first RAT is quieted during certain times to allow for a second RAT to operate without interference. Gap patterns may be constructed based on timeline constraints, such as grant scheduling and HARQ performance, or based on desired performance levels of one or more of the RATs. Gap patterns may be selected by a user equipment or base station. Gap patterns may be selected to protect information in certain subframes. Potential gap patterns may be assigned weights indicating their desirability.