MIMO Pilot Time Slot Allocation for Dense Terminals
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Solution Overview
Problem
Conventional MIMO systems face challenges in efficiently allocating pilot signaling resources, particularly when the number of terminals exceeds the available pilot time slots, leading to increased pilot signaling time that can negatively impact payload data transmission.
Innovation Solution
The method involves assigning multiple terminals to share the same orthogonal channel or pilot time slot, allowing them to transmit pilot signals in an alternating fashion, with the base station controlling the repetition rate and frame alignment to prevent simultaneous transmissions and optimize resource use.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If the number of pilot time slots is increased to accommodate more terminals, then the pilot signaling capability is improved, but the time available for payload data transmission is reduced
Solution Approach 1:
Multiple terminals are merged into the same pilot time slot to share the channel resource. The base station assigns multiple terminals to transmit pilot signals in a shared time slot using different orthogonal codes, thereby reducing the total number of pilot time slots needed and preserving time for payload data transmission.
Solution Approach 2:
A single pilot time slot is made universal by allowing multiple terminals to share it through code division multiplexing. The same time slot serves multiple terminals simultaneously, increasing the utility of each time slot and reducing the overall pilot signaling time required.
2Measurement precision
If separate pilot time slots are allocated to each terminal, then the pilot signaling accuracy is improved, but the resource efficiency deteriorates when the number of terminals exceeds available time slots
Solution Approach 1:
Orthogonal codes are introduced as an intermediary dimension to resolve the conflict between terminal quantity and time slot availability. By multiplying the coding dimension, multiple terminals can be distinguished within the same time slot, maintaining measurement precision while improving resource efficiency.
Solution Approach 2:
The system transitions from one-dimensional time division to two-dimensional code division within time slots. This dimensional expansion allows multiple terminals to share the same time resource while maintaining distinguishability through orthogonal coding, thus improving productivity without sacrificing measurement precision.
3Measurement precision
If the pilot signaling time is increased to cover all terminals, then the channel estimation accuracy is improved, but the data transmission throughput is reduced
Solution Approach 1:
Multiple terminals' pilot signaling is merged into shared time slots through orthogonal coding. This consolidation reduces the total pilot signaling time required while maintaining channel estimation accuracy, thereby increasing the time available for data transmission and improving throughput.
Solution Approach 2:
Terminals share pilot time slots in a periodic alternating fashion. Within each frame, terminals transmit pilot signals in an organized sequence using orthogonal codes, allowing the system to maintain accurate channel estimation with reduced overall signaling time, thus preserving data transmission throughput.
Data Source
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AI summary
A cellular multiple-input and multiple-output, MIMO, system (10) comprises a base station (20) having a plurality of antennas (22) and a logic (21) which analyzes pilot signals received from a terminal (11-15) at the plurality of antennas (22) to obtain information about radio channel properties between the terminal (11-15; 100) and the plurality of antennas (22). The base station (20) assigns at least two terminals (11-13) of a plurality of terminals (11-15) to a same pilot time slot. The base station (20) requests at least two terminals (11-13) to transmit pilot signals in the allocated pilot time slot in such a manner that the at least two terminals (11, 12; 11-13) are prevented from transmitting their pilot signals simultaneously.