MU-MIMO Pilot Sending Method Using Spreading Codes
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Solution Overview
Problem
In MU-MIMO communication systems, the large number of precoding matrix indexes required for users consumes significant network resources, leading to potential decoding failures due to simultaneous notification challenges.
Innovation Solution
The method involves spreading multiple signature sequences using a single spreading code, which are then precoded and sent as dedicated pilots to user equipment (UEs) for precoding matrix estimation, eliminating the need to send individual precoding matrix indexes and reducing resource consumption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a large number of precoding matrix indexes are sent to users, then users can perform accurate precoding matrix estimation, but network resources are consumed significantly
Solution Approach 1:
The patent combines multiple signature sequences and spreads them using a single spreading code to form dedicated pilots. This merging approach allows multiple users to share the same spreading code resource while maintaining their individual pilot sequences, thereby reducing the overall number of spreading codes needed and saving network resources while still providing accurate precoding matrix estimation capability.
Solution Approach 2:
The patent makes a single spreading code serve multiple functions by using it to spread multiple signature sequences that act as dedicated pilots for different users. This multi-functionality allows the same spreading code resource to support multiple users simultaneously, reducing the total quantity of spreading codes required in the system.
2Reliability
If individual precoding matrix indexes are sent to each user, then users can decode their data accurately, but the system complexity increases due to simultaneous notification challenges
Solution Approach 1:
The patent extracts the essential information needed for precoding matrix estimation from the individual precoding matrix indexes and embeds it directly into the dedicated pilots through signature sequences. By taking out the explicit index notification requirement and replacing it with implicit pilot-based estimation, the system reduces notification complexity while maintaining decoding accuracy.
Solution Approach 2:
The patent enables users to self-estimate their precoding matrices by processing the received dedicated pilots and signature sequences. Instead of relying on the network to explicitly notify each user of their precoding matrix index, users autonomously perform the estimation using the pilot signals, thereby simplifying the network's notification burden while ensuring accurate decoding.
3Measurement precision
If dedicated pilots are sent for each data stream, then users can perform precoding matrix estimation, but the number of required downlink channels increases
Solution Approach 1:
The patent merges multiple signature sequences into a single downlink channel by spreading them with a common spreading code. This combination allows multiple dedicated pilots to be transmitted through what effectively becomes a shared channel structure, reducing the number of separate downlink channels required while maintaining the ability to provide dedicated pilot signals to multiple users.
Data Source
AI summary
Embodiments of the present invention provide a pilot sending method and an apparatus, which relate to the communication field and can save network resources. The solution is: performing spreading on at least two signature sequences by using a spreading code, where each signature sequence of the at least two signature sequences corresponds to at least one user equipment (UE), and is used as a dedicated pilot of at least one data stream of the at least one UE, and the dedicated pilot is used by the UE to perform precoding matrix estimation; and performing precoding on the spread signature sequences, and sending the precoded spread signature sequences to the UE. The embodiments of the present invention are applicable to the sending of pilots in MU-MIMO.