Lbt parameters for uplink in unlicensed spectrum

Abstract

According to some embodiments, a method for use in a user equipment (UE) of managing a listen-before-talk (LBT) contention window size comprises transmitting a first burst of uplink subframes after a first LBT procedure performed using an LBT contention window size, and determining a reference subframe based on the first burst. The reference subframe is associated with a reference hybrid automatic repeat request (HARQ) process identifier. The method further comprises receiving scheduling for a second burst of uplink subframes. The scheduling comprises an associated HARQ process identifier and an associated new data indicator (NDI) for each subframe. When the UE determines the HARQ process identifier associated with at least one of the subframes of the second burst matches the reference HARQ process identifier, then if the associated NDI indicates new data, the method resets the LBT contention window size, else the method increments the LBT contention window size.

Description

TECHNICAL FIELD[0001]Particular embodiments are directed to wireless communications and, more particularly, to methods and apparatus for signaling and management of listen-before-talk (LBT) parameters for uplink transmission in unlicensed spectrum.INTRODUCTION[0002]The Third Generation Partnership Project (3GPP) initiative referred to as License Assisted Access (LAA) enables long term evolution (LTE) equipment to operate in the unlicensed 5 GHz radio spectrum. The unlicensed 5 GHz spectrum is used as a complement to the licensed spectrum. Accordingly, devices connect in the licensed spectrum (primary cell or PCell) and use carrier aggregation to benefit from additional transmission capacity in the unlicensed spectrum (secondary cell or SCell). To reduce the changes required for aggregating licensed and unlicensed spectrum, the LTE frame timing in the primary cell is simultaneously used in the secondary cell.[0003]The standalone LTE-U forum and 3GPP Rel-14 work item on Uplink License...

AI Technical Summary

Benefits of technology

The patent describes a way of efficiently sending parameters for a type of signaling called "listen-before-talk" (LBT) to user equipment (UE) while meeting requirements for managing contention windows. The system adjusts the size of the contention window based on the radio conditions during the beginning of a transmission. By doing so, it can improve the performance of uplink and system by reducing the amount of signaling and network load. The network can also closely track the adjustment at the UE.

Problems solved by technology

Regulatory requirements may not permit transmissions in the unlicensed spectrum without prior channel sensing.

The signaling parameters, however, do not fully encompass all the use cases and problems that may be encountered for uplink transmissions in unlicensed spectrum.

Effectively, if several access points are within range of each other, they will need to share the channel in time, and the throughput for the individual access points may be severely degraded.

The spectrum allocated to LTE, however, is limited.

It may not meet the ever increasing demand for larger throughput from applications / services.

Existing signaling and contention window management methods, however, do not fully account for the problems that arise when using implicit signaling to indicate contention window size that the UE must use.

When explicit signaling is used, it creates unnecessarily large signaling overhead.

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