Radio Device Multiplexed Data Sequences Unequal Power Allocation
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Solution Overview
Problem
Pilot contamination is a significant limiting factor in massive MIMO systems, particularly in TDD and FDD systems, due to intercell interference caused by the reuse of orthogonal pilot sequences, which leads to energy spillage and reduced performance.
Innovation Solution
Introducing a scheme that time-shifts uplink pilots with respect to neighboring cells and employs unequal power allocation between pilot and uplink data transmissions, mitigating pilot contamination by optimizing power distribution based on average power constraints and performance metrics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If orthogonal pilot sequences are reused in neighboring cells to meet higher data rate demands, then resource utilization is improved, but pilot contamination occurs causing intercell interference
Solution Approach 1:
The system segments the pilot transmission time by introducing a time offset between neighboring cells. Each cell transmits pilots in different time slots, dividing the originally simultaneous transmission into separated time segments. This eliminates pilot contamination while maintaining resource reuse, as each cell's pilot sequence is transmitted in its own time window without overlapping with neighbors.
Solution Approach 2:
The system implements periodic pilot transmission with different time offsets for different cells. Each cell periodically transmits pilots according to its assigned time offset pattern, creating a cyclic structure where pilot transmissions are staggered across cells. This periodic staggering ensures that while one cell transmits pilots, neighboring cells are in their data transmission phase, eliminating interference.
2Device complexity
If time-aligned pilot phases are used in adjacent cells for simplified synchronization, then system complexity is reduced, but intercell interference increases due to energy spillage
Solution Approach 1:
The system applies different time offset configurations to different cells based on their local characteristics and interference patterns. Each cell is assigned a specific time offset value that optimizes its performance while considering the interference environment. This localized configuration allows each cell to operate with optimized pilot timing rather than uniform alignment, reducing overall intercell interference.
3Ease of operation
If equal power allocation is used between pilot and data transmission for simplicity, then implementation is easier, but pilot contamination effect is not mitigated
Solution Approach 1:
The system changes the power allocation parameter from equal to unequal distribution between pilot and data transmissions. By allocating different power levels, the system can optimize the pilot transmission power to be sufficiently high for accurate channel estimation while limiting the data transmission power during pilot phases to reduce interference. This parameter adjustment directly addresses pilot contamination by controlling the relative power levels.
Solution Approach 2:
The system dynamically adjusts power allocation between pilot and data transmissions based on the transmission phase and interference conditions. During pilot phases, power is allocated differently than during data phases, and this allocation can be adapted based on channel conditions and interference levels. This dynamic power management enables effective mitigation of pilot contamination while maintaining overall system performance.
4Measurement precision
If pilot transmission power is increased to improve channel estimation accuracy, then measurement precision is improved, but intercell interference from data transmission increases
Solution Approach 1:
The system takes preliminary anti-action by reducing data transmission power before pilot transmissions occur in neighboring cells. By proactively lowering the power level during data phases that overlap with neighbor pilots, the system prevents interference from escalating. This preemptive power control ensures that when pilots are transmitted, the interfering data signals from other cells are already suppressed.
Data Source
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AI summary
The disclosure relates to a radio device (300), in particular a user equipment, for communication with a radio cell (110), the radio device (300) comprising: a processor (301), configured: to generate (302) a radio frame (211) comprising a first data sequence (101a) and a second data sequence (102a), to arrange (303) the first data sequence (101a) within the radio frame (211) in a time interval (212) that is non-overlapping with respect to a predetermined time interval (222, 232) of a first data sequence (101b, 101c) of another radio device with another adjacent radio cell (120, 130), and to apply (304) an unequal power allocation for generating the first data sequence (101a) and the second data sequence (102a).