Unlicensed Spectrum Access via Preliminary Base Station Contention
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Solution Overview
Problem
Existing wireless communication systems face inefficiencies in accessing unlicensed radio frequency spectrum bands due to the uncertainty of contention for channel access, leading to prolonged periods before a user equipment (UE) can transmit an access request, especially when the base station has not won channel access.
Innovation Solution
The proposed solution involves a UE transmitting a random access request in identified subframes of a listen before talk (LBT) radio frame, with specific subsets of symbols designated for contention-based access and message transmission, allowing for reduced channel contentions and more efficient Radio Resource Control (RRC) connection setup procedures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a UE performs a random access procedure requiring base station channel access contention in an unlicensed radio frequency spectrum band, then the access procedure follows standard LTE/LTE-A protocols, but the uncertainty of contention for channel access leads to prolonged periods before the UE can transmit an access request
Solution Approach 1:
The base station performs preliminary channel access contention and secures channel occupancy before the UE needs to transmit its access request. By winning channel access in advance and maintaining channel occupancy, the base station ensures that the channel is reserved and available when the UE needs to transmit, eliminating the need for the UE to perform separate contention procedures and reducing access delay.
2Productivity
If a base station wins channel access in an unlicensed radio frequency spectrum band, then the base station can transmit and receive signals, but the base station may not always win channel access leading to access procedure inefficiency
Solution Approach 1:
The base station performs channel access contention in advance of the UE's access request transmission. By securing channel occupancy beforehand, the base station ensures channel availability is established prior to needing it for the access procedure, improving both efficiency and reliability.
Solution Approach 2:
The base station monitors the outcome of channel access contention and adjusts its channel occupancy maintenance strategy based on whether it won or lost access. This feedback mechanism allows the base station to adapt its behavior to current channel conditions, improving overall access procedure efficiency.
Data Source
AI summary
Techniques are described for wireless communication. One method includes winning a contention for access to an unlicensed radio frequency spectrum band, transmitting a request message upon winning the contention for access to the unlicensed radio frequency spectrum band, and receiving a response message over the unlicensed radio frequency spectrum band. The request message is transmitted by a user equipment (UE) on an enhanced physical random access channel (ePRACH) or shortened ePRACH (SePRACH), to access a cell that operates in the unlicensed radio frequency spectrum band. The response message is received in response to transmitting the request message, and the request message may be transmitted irrespective of whether a base station has gained access to the unlicensed radio frequency spectrum band.