Multi-Radio Coexistence Manager for LTE and WLAN Interference
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Solution Overview
Problem
Conventional LTE systems face coexistence issues due to interference with other radios, such as Bluetooth and WLAN, within multi-radio devices, leading to unacceptable error rates and disruption in voice services, as the eNB is not adequately aware of interference on the UE side, resulting in unresolved uplink coexistence problems that degrade performance and efficiency.
Innovation Solution
The UE autonomously declares a Radio Link Failure, switches to a new channel or RAT, and communicates this issue to the eNB, allowing the eNB to become aware of coexistence problems and facilitating coordinated solutions, while the UE and eNB cooperate to mitigate interference through channel monitoring and scheduling.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If LTE uplink communication is active, then LTE data transmission is improved, but interference with Bluetooth and WLAN radios occurs causing unacceptable error rates
Solution Approach 1:
The patent implements time-division multiplexing where the LTE radio and ISM radios (Bluetooth/WLAN) operate in periodic time slots. The LTE uplink transmission is scheduled during specific time slots while ISM radios are muted, and vice versa. This periodic alternation allows both LTE productivity and ISM reliability to be maintained without continuous interference.
Solution Approach 2:
The system dynamically adjusts the operation state of different radios based on real-time scheduling decisions. The LTE radio can be activated or muted dynamically depending on whether an uplink time slot is allocated, and the ISM radios are dynamically muted during LTE uplink slots. This dynamic control resolves the contradiction by adapting radio operation to instantaneous system needs.
2Productivity
If LTE uplink transmission is scheduled, then LTE communication efficiency is improved, but coexistence issues with ISM band radios arise causing service disruption
Solution Approach 1:
The patent establishes a preliminary coordination mechanism where the LTE radio and ISM radios negotiate and agree on time slot allocation before actual communication begins. The LTE radio is configured with knowledge of upcoming uplink time slots in advance, allowing it to proactively mute during these periods to prevent interference with ISM voice services, ensuring seamless operation.
3Adaptability or versatility
If multiple radios operate simultaneously, then device functionality is improved, but in-device interference occurs degrading overall performance
Solution Approach 1:
The patent segments the time domain into distinct time slots allocated to different radio types. Instead of allowing all radios to operate simultaneously in the entire time domain, the system divides time resources so that LTE uplink transmissions and ISM radio operations occur in separate, non-overlapping time segments. This segmentation maintains multi-radio functionality while eliminating interference.
Solution Approach 2:
The patent introduces a coexistence manager or coordination mechanism that acts as an intermediary between the LTE radio and ISM radios. This intermediary negotiates time slot allocations, monitors interference conditions, and coordinates the operation of different radios to ensure they do not interfere with each other, thereby maintaining reliable coexistence while preserving versatile functionality.
Data Source
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AI summary
Interference between potentially conflicting radio access technologies (RATs) in a wireless device may be managed through a coexistence manager which allows communication using a first active RAT (e.g., Long Term Evolution (LTE)) and communication with a second active RAT (e.g., wireless local area network (WLAN)) when the first RAT is not scheduled for communicating during an uplink timeslot. Communications by a WLAN radio may be controlled using a power save mode. WLAN communications may be timed so that downlink signals (such as data or acknowledgement messages) to the WLAN radio are received during an inactive uplink subframe for an LTE radio. WLAN communications may also be timed so that downlink signals to the WLAN radio are received during downlink times scheduled for an LTE radio.