Dynamic Reference Signal Allocation for Uplink Capacity
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Solution Overview
Problem
Existing wireless communication systems face challenges in efficiently using reference signals for uplink transmission, particularly in managing the limited number of Demodulation Reference Signals (DRSs) to support multiple users and antennas, which leads to suboptimal channel estimation and capacity utilization.
Innovation Solution
The method involves dynamically adjusting the number of virtual antennas and corresponding DRSs per user, controlled by a Central Node, to optimize the use of reference signals. This approach allows for adaptive allocation based on channel conditions, uplink load, and system load, ensuring sufficient DRSs for effective channel estimation and capacity enhancement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If transmit diversity is used for all users to improve SNR and coverage, then reliability is improved, but the number of reference signals consumed increases unnecessarily for users with already high SNR
Solution Approach 1:
The patent applies local quality by differentiating reference signal allocation based on individual user channel conditions. Users with high SNR (good channel conditions) are allocated fewer reference signals, while users with low SNR (poor channel conditions) are allocated more reference signals. This localized adaptation resolves the contradiction by providing transmit diversity only where it is genuinely needed, rather than uniformly to all users.
2Productivity
If multiple physical antennas are used per user for spatial multiplexing to increase capacity, then productivity is improved, but the number of orthogonal reference signals required increases
Solution Approach 1:
The patent applies dynamics by making the number of reference signals allocated to each user adaptable rather than fixed. The central node dynamically adjusts the number of reference signals based on real-time channel conditions, uplink load, and system load. This allows the system to optimize spectral efficiency by using multiple antennas when channel conditions support it, while consuming fewer reference signals when conditions are poor, thus resolving the contradiction between capacity and reference signal consumption.
3Productivity
If the number of simultaneously multiplexed users is increased to improve system capacity, then productivity is improved, but the available orthogonal reference signals are depleted
Solution Approach 1:
The patent applies parameter changes by modifying the reference signal allocation parameters dynamically. Instead of allocating a fixed number of reference signals to each user, the central node adjusts the number of reference signals based on current system conditions including the number of active users, channel quality, and load conditions. This parameter adaptation allows the system to support more simultaneously multiplexed users by optimizing reference signal distribution, thus resolving the contradiction between system capacity and reference signal availability.
Data Source
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AI summary
The present invention relates to a method in a Central Node (CN), a method in a Remote Node (RN), and a method in a wireless communication system for allocating reference signals to be used for uplink transmission. According to one aspect of the invention reference signals are allocated with a method comprising the steps of: determining in a CN a number of reference signals N to be used for uplink transmission by a Remote Node RN; indicating to the RN the number of reference signals N to be used for uplink transmission by the RN; configuring an uplink transmission by the RN with at most the number of reference signals N; and performing by the RN the uplink transmission with at most the number of reference signals N on transmit antennas comprised in the RN. The present invention further discloses a CN and a RN relating to said methods.