Pilot Signal Assignment via Multicast Channel Estimation
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Solution Overview
Problem
In massive-MIMO radio transmission systems, the increased user density leads to frequent collisions of pilot signals during first-time access, causing delays and inefficient use of radio resources, as user equipments randomly select pilot signals, resulting in collisions and the need for reattempts.
Innovation Solution
A method where a radio base station estimates a multicast channel and computes combined signal power for user equipments with colliding pilot signals, sending a message to assign different pilot signals based on individual signal powers, thereby avoiding collisions and reattempts by distinguishing user equipments based on their signal power contributions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If user equipments randomly select pilot signals for first-time access, then the selection process is simple and fast, but pilot signal collisions occur frequently leading to access delays
Solution Approach 1:
The base station provides feedback to user equipments about pilot signal collisions by estimating combined signal power and sending assignment messages. This feedback mechanism allows UEs to adjust their pilot signal selection based on collision information, resolving the contradiction between simple random selection and avoiding collisions that cause delays
Solution Approach 2:
The base station performs preliminary channel estimation and collision detection before final pilot signal assignment. By estimating the multicast channel and computing combined signal power in advance, the system can identify collisions early and assign different pilot signals before access attempts are made, preventing delays
2Quantity of substance
If the length of pilot signals is increased to provide more distinct signals, then the number of available pilot signals increases, but more radio capacity is occupied reducing payload data transmission
Solution Approach 1:
The system changes the parameter of pilot signal assignment from fixed random selection to dynamic assignment based on signal power characteristics. By computing combined signal power and using this parameter to assign different pilot signals, the system increases the effective number of available pilot signals without increasing their length, thus preserving radio capacity for payload data
3Reliability
If user equipments reattempt access after pilot signal collisions, then collision-free access can eventually be achieved, but additional radio resources are occupied and delays increase
Solution Approach 1:
The base station performs preliminary collision detection and pilot signal assignment before access attempts. By estimating the multicast channel and assigning different pilot signals in advance based on combined signal power calculations, the system ensures collision-free access from the first attempt, eliminating the need for reattempts and preserving radio resource efficiency
Data Source
AI summary
A technique for assigning pilot signals to user equipments is described. The UEs access an RBS that provides radio access. As to a method aspect of the technique, an access burst including initial pilot signals is received from the UEs, wherein at least two of the UEs apply simultaneously the same initial pilot signal. A multicast channel to the at least two UEs is estimated based on the received access burst. A combined signal power received at the RBS is computed for the at least two UEs based on the estimated multicast channel. A message to the at least two UEs is sent using the multicast channel. The message is indicative of the combined signal power and assigns different pilot signals to the at least two UEs, wherein the assignment depends for each of the at least two UEs on the combined signal power and a signal power received at the respective UE.