Pilot Allocation in Multi-Antenna Systems
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Solution Overview
Problem
In multi-antenna communication systems, especially those using the millimeter wave band, the increased number of beams leads to high overhead and interference issues when allocating pilots, which deteriorates communication capacity and channel estimation performance.
Innovation Solution
The method involves configuring pilot signals into two sets that use the same resources but are distinguished by different random numbers and orthogonal codes, allowing for efficient allocation and transmission to minimize interference between pilots during spatial multiplexing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If independent allocation of pilots is performed for each beam, then channel estimation performance is improved, but system overhead increases and communication capacity deteriorates
Solution Approach 1:
Multiple pilots that would traditionally be allocated independently to different beams are merged into a single pilot signal that is transmitted across multiple beams simultaneously. This combining approach reduces the total number of pilots required while maintaining channel estimation capability for multiple beams through the shared pilot structure.
Solution Approach 2:
A single pilot signal is designed to serve multiple functions by being transmitted across multiple beams simultaneously. This universal pilot can be used for channel estimation in multiple beams, eliminating the need for separate dedicated pilots for each beam and thereby reducing system overhead.
2Measurement precision
If multiple pilots are transmitted for multiple beams, then channel estimation is enabled, but interference between pilots increases
Solution Approach 1:
Orthogonal codes are introduced as an intermediary mechanism to distinguish between multiple pilots that are transmitted simultaneously across different beams. These orthogonal codes act as mediators that allow the pilots to share the same time-frequency resources while maintaining separability and minimizing interference through orthogonal separation.
Solution Approach 2:
Different orthogonal codes are assigned to different beams or pilot groups, creating locally distinguishable characteristics. This allows each beam's pilot to be identified and processed independently despite being transmitted simultaneously, reducing interference through localized differentiation via orthogonal coding.
3Productivity
If the number of antennas is increased for millimeter wave communication, then communication capacity is improved, but pilot allocation complexity increases
Solution Approach 1:
The set of available pilots is segmented into multiple groups or sets, where each segment can be allocated to different beams or antenna groups. This segmentation allows for systematic pilot allocation across a large number of antennas while maintaining manageable complexity through structured distribution patterns.
Solution Approach 2:
The pilot allocation strategy is made dynamic by allowing flexible mapping between pilots and beams based on current system conditions. This dynamic allocation enables efficient use of pilots across varying numbers of antennas and beams, adapting to different communication scenarios without requiring fixed complex allocation procedures.
Data Source
AI summary
A method in which a base station transmits pilot signals in a multiple-antenna communication system is provided. The base station includes some of the plurality of pilot signals distinguished by at least one of time domain symbols, subcarriers, and orthogonal codes in a first set to which a first random number is applied. The base station includes the remaining pilot signals, excluding the pilot signals that are included in the first set, in a second set that uses the same resources as used by the first set and to which a second random number different from the first random number is applied. The base station transmits at least one of the pilot signals that belong to the first set and the second set.