Null Tone Pattern for Interference Detection in Shared Spectrum
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Solution Overview
Problem
As cellular networks become congested, the offloading of traffic from licensed radio frequency spectrum to unlicensed or shared spectrum leads to interference between WWAN and WLAN signals, causing bursty interference that affects transmission rates and overall network performance.
Innovation Solution
A base station generates a null tone pattern for subframes, which includes null tones mapped to subcarriers within consecutive symbols in each resource block, allowing user equipment (UE) to detect and mitigate interference caused by WLAN and WWAN nodes operating in unlicensed or shared spectrum by determining null tone density and transmitting this pattern to UEs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If traffic is offloaded from licensed spectrum to unlicensed or shared spectrum, then network capacity is increased, but interference between WWAN and WLAN signals occurs
Solution Approach 1:
The patent introduces null tones as intermediary elements that mediate between WWAN and WLAN signals. These null tones are inserted at specific resource elements to indicate to UEs where interference is expected, allowing the system to coexist in shared spectrum without direct conflict between the two technologies
Solution Approach 2:
The base station performs preliminary action by pre-configuring null tone patterns and transmitting them to UEs before actual data transmission. This allows UEs to anticipate and prepare for interference conditions, adjusting their reception parameters in advance to mitigate the harmful effects of bursty interference
2Measurement precision
If null tones are inserted to detect interference, then interference detection capability is improved, but resource efficiency decreases
Solution Approach 1:
Instead of applying null tones uniformly across the entire frequency spectrum, the patent applies them locally at specific resource elements where interference is most likely to occur. This localized approach maintains interference detection capability while minimizing the overall resource overhead
Solution Approach 2:
The patent implements partial action by inserting null tones only in certain subframes and at specific resource elements rather than continuously across all resources. This partial application provides sufficient interference detection capability while reducing the total resource consumption compared to full-spectrum null tone insertion
Data Source
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AI summary
Systems, methods, and apparatuses for detecting interference caused by a wireless local area network (WLAN) and a wireless wide area network (WWAN) node operating in an unlicensed or shared spectrum is disclosed. In accordance with the present disclosure, a base station may generate a null tone pattern for one or more subframes transmitted to the UE. The null tone pattern may include one or more null tones mapped to consecutive symbols in each resource block to detect interference. Accordingly, a UE may monitor a wireless channel from a base station for a null tone transmission. The UE may detect a null tone pattern by decoding a known physical layer channel to identify the null tone pattern. In some aspects, the UE may generate channel estimates, decode allocated resources, determine timing of future transmissions and/or establish communication with the base station based on the identified null tone pattern.