Unlicensed Spectrum Channel Partitioning for Flexible FDD Access
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Solution Overview
Problem
Existing communication systems in unlicensed spectrum face inefficiencies and increased latency due to scanning procedures like listen before talk (LBT), which can lead to channel access delays and interference, especially when using flexible frequency division duplex (FDD) techniques.
Innovation Solution
Nodes are configured to assess transmission opportunities using flexible frequency division duplex (FDD) techniques, allowing transmissions to occur in non-overlapping portions of channels even when other nodes are using the channel, thereby reducing or eliminating the need for full LBT procedures and improving communication efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If scanning procedures like listen before talk (LBT) are performed prior to transmission in unlicensed spectrum, then interference is mitigated and fair sharing is achieved, but latency increases and channel access delays occur
Solution Approach 1:
The channel is divided into multiple sub-channels or frequency portions. The node performs LBT scanning on only the specific sub-channel or frequency portion where transmission is needed, rather than scanning the entire channel bandwidth. This segmentation reduces the scanning time and latency while still ensuring fair sharing and interference mitigation on the accessed portion.
Solution Approach 2:
Instead of performing complete LBT procedures on all channels before transmission, the node performs partial LBT scanning only on the necessary frequency portions or sub-channels. This partial action reduces the time and complexity of the scanning procedure while maintaining adequate interference mitigation for the actual transmission.
2Productivity
If nodes transmit on multiple channels to increase throughput and reliability, then communication efficiency improves, but channel access complexity and interference management increase
Solution Approach 1:
The node divides the available channel bandwidth into multiple sub-channels and selectively accesses only those sub-channels where LBT scanning succeeds. This allows parallel transmission on multiple sub-channels, increasing throughput while keeping the complexity of each individual channel access relatively simple.
Solution Approach 2:
The node dynamically selects which sub-channels to transmit on based on real-time LBT scanning results. This dynamic adaptation allows the system to exploit available spectrum opportunities across multiple channels while managing access complexity through flexible, condition-based channel selection.
3Reliability
If full LBT procedures are performed before each transmission, then fair sharing of unlicensed spectrum is ensured, but channel usage efficiency decreases
Solution Approach 1:
The node segments the channel access process by performing LBT scanning independently on different sub-channels or frequency portions. This allows the node to access available portions of the spectrum without being blocked by busy portions, improving channel usage efficiency while still ensuring fair sharing through proper LBT procedures on accessed segments.
Solution Approach 2:
The node applies LBT scanning locally to specific sub-channels or frequency portions where transmission is intended, rather than uniformly across the entire channel. This local approach ensures fair sharing on the accessed portions while avoiding unnecessary delays from scanning entire channels that may have available capacity elsewhere.
Data Source
AI summary
A node configured to support a method of communicating between two nodes in the unlicensed spectrum is disclosed where a channel can be simultaneously used for downlink and uplink communication. The method performed at a node involves assessing at that node, for example, a UE, that there is a transmission to be made to a further node, for example a gNB. The first node receives an indication that communication with the further node is supported on a channel within an unlicensed spectrum using flexible frequency division duplex (FDD) techniques. The first node determines whether transmission by the further node is being made within a first portion of the channel within the unlicensed spectrum; and if so, transmits to the further node within a second portion of the channel which does not overlap with the first.