Opportunistic Extended Channel Uplink Grants for Wireless Systems
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Solution Overview
Problem
In contention-based wireless communication systems, the existing clear channel assessment (CCA) procedures can lead to delayed transmissions or reduced effective bandwidth due to failed extended CCA (eCCA) at base stations, even if channels are available from the user equipment (UE) perspective.
Innovation Solution
Implementing an opportunistic extended channel uplink grant mechanism where a base station sends grants for channels that passed a single CCA but not eCCA, allowing the UE to perform a single CCA on granted channels and an eCCA on others, enabling transmission even if the base station's eCCA fails.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the base station performs extended CCA (eCCA) on all channels before sending grants, then channel availability is ensured from the base station perspective, but transmission delays occur and effective bandwidth is reduced when eCCA fails even though channels may be available from UE perspective
Solution Approach 1:
The patent segments the CCA procedure into two distinct types: single CCA for the first channel (used for receiving scheduling messages) and extended CCA (eCCA) for the second channel (used for uplink transmission). This segmentation allows the UE to perform different clearance procedures on different channels based on their specific roles and requirements, resolving the contradiction by enabling faster access on the scheduling channel while maintaining reliability on the data channel.
Solution Approach 2:
The patent inverts the traditional approach by having the base station send scheduling messages on a first channel that requires only single CCA, rather than requiring eCCA on all channels. The UE receives grants on the easily-accessible first channel and then performs eCCA only on the second channel for actual data transmission. This inversion allows the system to bypass eCCA delays on the control channel while maintaining reliability on the data channel.
2Reliability
If the base station requires eCCA to pass before sending uplink grants, then channel reliability is improved, but channel utilization and bandwidth efficiency are reduced
Solution Approach 1:
The patent applies local quality by imposing different CCA requirements on different channels based on their specific functions. The first channel (used for scheduling messages) requires only single CCA for quick access, while the second channel (used for uplink data) requires eCCA for reliable transmission. This localized differentiation allows the system to maintain high channel utilization on the control channel while ensuring reliability on the data channel, resolving the contradiction between reliability and productivity.
Solution Approach 2:
The patent performs preliminary CCA on the first channel at the UE side before receiving scheduling messages, and performs eCCA on the second channel after receiving grants but before transmission. This preliminary action on the first channel using single CCA allows the UE to quickly determine if the scheduling channel is available, improving channel utilization without compromising the reliability of actual data transmission on the second channel.
Data Source
AI summary
Methods, systems, and devices for wireless communication are described. A wireless communication system may utilize a listen before talk (LBT) procedure prior to transmission. A base station may perform an enhanced clear channel assessment (eCCA) on one channel and a single clear channel assessment (CCA) on another channel. The base station may then send a grant for a user equipment (UE) to transmit on both channels. The UE may receive the grant, and perform a single CCA on the first channel and an eCCA on the second channel. The UE may then transmit uplink information on both the first channel and the second channel. That is, the base station may send an opportunistic grant for transmitting on the second channel even though it may not have passed eCCA at the base station. The UE may then use the channel if it passes an eCCA.