Massive MIMO Cell Access via Base Station Channel Measurement
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Solution Overview
Problem
The introduction of massive MIMO technology to micro cells faces challenges in cell selection and access due to the need for precise channel information, which is lacking for user equipment during initial access, and the high cost and size of W-level power amplifiers, limiting the deployment of mW-level power amplifiers that could reduce costs and size.
Innovation Solution
A method where a micro-cell base station measures and analyzes uplink access requests and reports measurement results to a macro-cell base station, enabling the macro-cell to replace user equipment in measuring downlink signals and providing feedback, thereby facilitating micro cell selection and access, while reducing power amplifier levels and improving hotspot capacity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Weight of stationary object
If mW-level power amplifier is used to replace W-level power amplifier, then cost and volume are reduced, but transmit power is reduced to below 1W and signal power is reduced by 16dB
Solution Approach 1:
The patent combines multiple antenna elements into a massive MIMO antenna system where multiple low-power amplifiers (mW-level) work together to provide the necessary aggregate transmit power and signal strength, replacing what would traditionally require a single high-power amplifier (W-level). The combined effect of multiple antenna beams achieves the required coverage while keeping individual amplifier power low.
Solution Approach 2:
The patent introduces precoding as an intermediary processing technique that weights and combines signals from multiple antenna elements before transmission. This precoding process compensates for the lower power of individual mW-level amplifiers by optimally distributing and combining their outputs to achieve the necessary signal strength at the user equipment, effectively mediating between low individual power and sufficient total signal strength.
2Power
If precoding is performed to meet link budget requirements, then signal strength is sufficient, but channel information is required which is not available during initial access
Solution Approach 1:
The patent performs preliminary channel estimation using reference signals (such as CSI-RS or CRS) that are transmitted before actual data transmission. This preliminary action provides the channel information needed for precoding to be established in advance, allowing the system to prepare precoding weights based on measured channel conditions before user equipment needs to access the network or before data transmission begins.
Solution Approach 2:
The patent enables user equipment to perform autonomous cell selection and access by having the device measure downlink reference signals and autonomously determine channel quality. The UE can self-estimate channel conditions and provide feedback or make access decisions without requiring complex base station intervention for channel measurement, allowing initial access to proceed without pre-established channel information.
3Ease of operation
If user equipment performs initial access without channel information, then access can be initiated, but downlink signal measurement and feedback cannot be performed
Solution Approach 1:
The patent uses downlink reference signals (such as CRS, CSI-RS, or synchronization signals) as intermediary carriers that convey channel information without requiring prior channel establishment. These reference signals are specifically designed to be measurable by user equipment during initial access, serving as a mediator that allows UE to obtain channel information autonomously while the network maintains flexibility in transmission strategies.
Solution Approach 2:
The patent segments the access process into distinct phases: first, UE performs autonomous cell search and synchronization using broadcast signals; second, UE measures downlink reference signals to estimate channel conditions; third, UE provides measurement feedback or autonomously selects cells based on measured quality. This segmentation allows initial access to proceed without pre-established channel information while still enabling subsequent precoding operations.
Data Source
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AI summary
Embodiments of the present invention disclose a base station, including: an initial access establishment module, adapted to establish initial access to user equipment; a channel resource negotiation module, adapted to: negotiate with a base station corresponding to a user cell to reserve, for the user equipment, a channel resource used for an access request, and send the user equipment the channel resource used for an access request; a channel quality receiving module, adapted to receive access request channel quality information reported by the base station corresponding to the user cell, where the access request channel quality information is access request channel quality information obtained by performing, by the base station corresponding to the user cell, channel quality analysis and measurement according to a received access request sent by the user equipment; a serving cell determining module, adapted to analyze and determine channel quality of the user cell according to the access request channel quality information, to select a user cell as a serving cell of the user equipment; and a data path configuration module, adapted to configure, for the user equipment, a path for data transmission to the serving cell.