CoMP Base Station CCA Coordination in Unlicensed Spectrum
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Solution Overview
Problem
In wireless communication networks, especially in heavily utilized cellular networks, there is a need to increase capacity by effectively utilizing unlicensed radio frequency spectrum bands, where coordination among base stations is required to ensure fair access and efficient use of the spectrum, particularly in contention-based scenarios where uncertainty exists about which base stations win channel access.
Innovation Solution
A method where base stations in a coordinated multi-point (CoMP) set perform a clear channel assessment (CCA) procedure to contend for access to the unlicensed radio frequency spectrum band, determining a CCA status and communicating it to other base stations, allowing coordinated communications with those that have won contention, including the exchange of channel state information (CSI) like a rank indicator (RI) for subsequent access attempts.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If base stations perform independent contention-based access in unlicensed spectrum, then each base station can access the channel independently, but coordination among base stations is lost and spectrum efficiency deteriorates
Solution Approach 1:
The patent merges independent contention-based access with coordinated multi-point transmission by having base stations share CCA results through backhaul communication. This allows base stations to maintain independent channel access capability while coordinating their transmissions to improve spectrum efficiency and enable CoMP operations in unlicensed bands.
2Productivity
If base stations coordinate transmissions in unlicensed spectrum, then spectrum efficiency and network capacity improve, but complexity of coordination increases
Solution Approach 1:
The patent applies preliminary action by having base stations exchange CCA status information before initiating coordinated transmissions. This preliminary coordination through backhaul communication allows base stations to prepare transmission resources and avoid conflicts, reducing the complexity of real-time coordination while maintaining high network capacity.
3Reliability
If base stations use listen-before-talk (LBT) approach, then fair spectrum access is ensured, but transmission delay increases
Solution Approach 1:
The patent employs periodic action by having base stations perform CCA procedures at regular intervals and share results through backhaul communication. This periodic coordination allows base stations to maintain fair spectrum access through LBT while reducing transmission delays by pre-coordinating access rights and preparing transmission resources in advance.
4Adaptability or versatility
If base stations share CCA status information, then coordinated multi-point transmissions are enabled, but communication overhead increases
Solution Approach 1:
The patent extracts only the essential CCA status information (success/failure state and duration) that base stations need for coordination, rather than sharing complete channel measurement data. This selective information exchange enables CoMP capability while minimizing communication overhead on the backhaul interface.
Data Source
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AI summary
Techniques are described for downlink coordinated multi-point (CoMP) procedures for access to a contention-based radio frequency spectrum band. A base station performs a contention procedure, such as a clear channel assessment (CCA) procedure, for access to the radio frequency spectrum band. The base station determines whether contention has been won for a time period, and communicates whether or not contention has been won to other base stations in a CoMP cooperating set. Based on the information exchanged between base stations in the CoMP cooperating set, coordinated communications is initiated to a UE with two or more of the base stations in the CoMP cooperating set.