LTE Channel Quality Indicator Adjustment for Multi-Radio Coexistence
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Solution Overview
Problem
Conventional LTE systems face coexistence issues due to interference between radios, such as LTE uplink signals interfering with Bluetooth or WLAN signals, leading to unacceptable disruptions and a lack of effective mechanisms to resolve these issues, as eNodeBs are not adequately aware of in-device interference, resulting in prolonged performance degradation.
Innovation Solution
A method and apparatus that alter channel measurement reports to create communication gaps in one radio access technology, allowing communication to occur using another radio access technology during these gaps, thereby mitigating interference by informing the eNodeB of coexistence issues and enabling autonomous channel changes by the UE.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If LTE uplink transmission is performed continuously, then LTE communication performance is maintained, but interference with Bluetooth and WLAN signals occurs causing unacceptable error rates and service disruptions
Solution Approach 1:
The patent implements periodic action by creating communication gaps in LTE uplink transmission at regular intervals. These gaps allow Bluetooth and WLAN radios to operate without interference from LTE signals. The network scheduler coordinates these gaps to maintain LTE performance while enabling ISM band communications, thus periodically alternating between LTE transmission and allowing ISM band operation.
Solution Approach 2:
The patent applies preliminary action by having the UE report altered channel measurement indicators to the network before interference occurs. This early warning system allows the network to proactively schedule communication gaps and coordinate multi-radio operation, preventing interference before it degrades Bluetooth or WLAN performance.
2Reliability
If the UE autonomously changes channels to avoid interference, then coexistence performance improves, but the network may handover back to the original corrupted channel causing a ping-pong effect
Solution Approach 1:
The patent implements feedback by having the UE continuously monitor for coexistence issues and report altered channel measurement indicators to the network. The network uses this feedback to make informed handover decisions, avoiding channels that would cause interference. This closed-loop feedback mechanism prevents the ping-pong effect by ensuring the network has accurate information about channel corruption before making assignment decisions.
Solution Approach 2:
The altered channel measurement indicator serves as an intermediary between the UE's autonomous channel selection and the network's handover decisions. This intermediary provides the network with corrected channel quality information that reflects actual coexistence conditions, enabling the network to act as a mediator that coordinates channel assignments to avoid both interference and unstable ping-pong handovers.
3Device complexity
If downlink interference estimates are used for handover decisions, then network coordination is simplified, but uplink coexistence issues are not detected causing unresolved interference
Solution Approach 1:
The patent applies self-service by having the UE independently measure and report uplink interference conditions through altered channel measurement indicators. Instead of relying on the network to detect uplink interference, the UE autonomously monitors its own transmission impact on ISM band radios and reports this information to the network, enabling the network to make informed decisions without increasing overall system complexity.
Data Source
AI summary
A method of wireless communication includes adjusting a channel quality indicator (CQI) to compensate for coexistence interference experienced between communication resources (such as an LTE radio and a Bluetooth radio). The CQI may be set to zero, falsely indicating to a serving enhanced NodeB that a UE is out of range, thereby creating a gap in LTE operation that may be used by an alternate radio access technology. To compensate for fluctuating interference, the CQI may be adjusted to incorporate average coexistence interference over a period of time. Alternatively, the CQI at a time may incorporate coexistence interference regardless of whether interference is experienced at that specific time. A CQI value may also be boosted to compensate for a CQI backoff. CQI may be adjusted to avoid a spiral of death effect.