LTE WLAN Coexistence via RF Collision Avoidance
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Solution Overview
Problem
Existing solutions for mitigating interference between co-located radio access technologies (RATs) in wireless devices, such as LTE and WLAN, either increase the size and noise figure of devices or sacrifice system throughput, and are insufficient to effectively address intermodulation distortion (IM3) issues.
Innovation Solution
Implementing RF collision avoidance techniques that allow concurrent operations by configuring transceivers to transmit a look-ahead signal, adjusting transmission schedules, and reducing OFDM carriers to prevent concurrent transmissions and minimize IM3, while ensuring sufficient frequency separation and antenna isolation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If sharp transmit and receive filters are added in the transceivers of co-located RATs, then interference between RATs is reduced, but device size and noise figure increase
Solution Approach 1:
The patent extracts and eliminates the need for bulky acoustic filters by implementing RF collision avoidance techniques. The system prevents concurrent transmissions between LTE and WLAN transceivers through scheduling coordination, thereby removing the requirement for physical filtering components and reducing device size.
Solution Approach 2:
The patent applies preliminary action by implementing look-ahead signaling between transceivers. The LTE transceiver notifies the WLAN transceiver of upcoming transmissions in advance, allowing the WLAN transceiver to preemptively suspend its transmission. This preventive scheduling avoids interference before it occurs, eliminating the need for reactive filtering.
2Object-affected harmful factors
If sharp transmit and receive filters are added in the transceivers of co-located RATs, then interference between RATs is reduced, but noise figure and insertion loss increase
Solution Approach 1:
The patent removes the need for acoustic filters that degrade link performance. By using RF collision avoidance and scheduling techniques, the system achieves interference mitigation without the noise figure penalty and insertion loss that would result from adding sharp filters in the signal path.
3Object-affected harmful factors
If scheduling and coordination between RATs is implemented to prevent concurrent transmissions, then interference is reduced, but system throughput is sacrificed
Solution Approach 1:
The patent implements preliminary action through look-ahead signaling, where the LTE transceiver notifies the WLAN transceiver of upcoming transmissions. This allows the WLAN transceiver to suspend transmission only when necessary, rather than continuously preventing concurrent operations. The selective and targeted scheduling preserves throughput by allowing concurrent transmissions when they do not cause interference.
4Object-affected harmful factors
If scheduling and coordination between RATs is implemented to prevent concurrent transmissions, then interference is reduced, but device complexity increases
Solution Approach 1:
The patent introduces an intermediary signaling mechanism where transceivers exchange look-ahead notifications. This simple mediator approach coordinates between LTE and WLAN transceivers without requiring complex centralized scheduling algorithms or changes to air interface standards. The intermediary signal enables decentralized coordination with minimal complexity.
Data Source
AI summary
Methods and configurations for mitigating intermodulation between a first transceiver and a co-located second transceiver are provided. A method includes determining when the transceivers are concurrently transmitting, and when they are concurrently transmitting, changing a transmission channel of the second transceiver to mitigate the intermodulation when it is determined that the intermodulation is affecting at least one of the first and second transceivers. The first method also includes sending a look-ahead signal from the first transceiver to the second transceiver indicating when the first transceiver will be transmitting, and completing all transmission activity of the second transceiver prior to a transmission by the first transceiver. A second method also includes implementing a schedule for the first transceiver, which designates regular transmission and reception opportunities, communicating the schedule to the second transceiver, and only allowing the second transceiver to transmit when a transmitter of the first transceiver is inactive.