Long Training Field Allocation in Multi-User MIMO Systems
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
In multi-user MIMO radio communication systems, the existing methods for transmitting long training fields (LTFs) result in increased overhead and reduced transmission efficiency, especially when supporting a large number of streams, leading to degraded channel estimation performance.
Innovation Solution
A method and apparatus that determine the number of long training fields for each station based on the number of transmission streams, calculate the least common multiple of these fields, and allocate them efficiently to reduce overhead and improve channel estimation by recombining and remapping LTFs according to channel status information.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the number of long training fields is increased to support more streams, then the channel estimation capability is improved, but the overhead and transmission efficiency are degraded
Solution Approach 1:
The patent divides the LTF allocation into user-specific portions based on the number of streams each user receives. Instead of allocating LTFs uniformly across all users, the system calculates the least common multiple of LTF counts for different users and segments the total LTF resources accordingly, allowing each user to receive appropriate LTF allocation proportional to their stream count.
Solution Approach 2:
The patent applies different LTF allocation strategies to different users based on their individual stream requirements. Users with more streams receive more LTFs, while users with fewer streams receive fewer LTFs. This localized differentiation ensures that each user receives the minimum necessary LTFs for accurate channel estimation without wasting resources on users who don't need as many.
2Measurement precision
If the number of long training fields is increased to support more streams, then the channel estimation capability is improved, but the overhead is increased
Solution Approach 1:
The patent segments the total LTF resources among multiple users based on their individual stream requirements. By calculating the least common multiple of LTF counts for different users and allocating proportionally, the system reduces the total number of LTFs needed compared to a uniform allocation approach, thereby reducing overhead while maintaining adequate channel estimation capability for each user.
Solution Approach 2:
The patent dynamically adjusts the number of LTFs allocated to each user based on the number of streams assigned to that user. This parameter change strategy ensures that LTF allocation is optimized rather than fixed, reducing overall overhead by avoiding unnecessary LTFs for users with fewer streams while maintaining sufficient LTFs for users with more streams.
3Ease of operation
If uniform long training field allocation is used for all users, then the allocation simplicity is maintained, but the transmission efficiency for users with fewer streams is degraded
Solution Approach 1:
The patent introduces dynamic LTF allocation that adapts to the number of streams assigned to each user. Instead of a static uniform allocation, the system calculates and adjusts LTF counts based on individual user requirements. This dynamic approach improves transmission efficiency for users with fewer streams by allocating them fewer LTFs, while the calculation process remains systematic and manageable.
Data Source
AI summary
An apparatus of transmitting a long training field includes: a station number determination unit configured to determine at least one station to be transmitted using transmission data or channel status information; a transmission stream allocation unit configured to determine the number of transmission streams for each of the least one station determined by the station number determination unit; a long training field number calculation unit configured to calculate the number of long training fields required for each of the at least one station determined by the transmission stream allocation unit and determines the least common multiple of the number of calculated long training fields of each station; and a long training field allocation unit configured to allocate the long training fields for each station to subcarriers allocated to each station to correspond to the least common multiple of the determined long training fields.