Base Station Front Haul Bandwidth Reduction via Layer Segmentation
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Solution Overview
Problem
Current LTE radio communication networks face challenges in reducing the bandwidth required for the front haul (FH) interface due to the distribution of functions between the central digital unit (DU) and remote radio unit (RU) in centralized radio access networks (C-RAN), particularly with the expected peak rates and latency improvements in 5G systems.
Innovation Solution
Implementing some functions of layer 1 and layer 2 on the RU side, with optimized parameter sharing and reduced signal transmission between the DU and RU, such as the PCFICH, PHICH, and PDCCH, to minimize the FH bandwidth requirements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Extent of automation
If all layer 1 and layer 2 functions are implemented on the DU side, then centralized control and management are improved, but the bandwidth required for the front haul interface increases significantly
Solution Approach 1:
The patent segments the base station functions by separating layer 1 and layer 2 processing between the RU and DU. Specifically, FFT, resource mapping, and physical channel generation are implemented on the RU side, while MAC layer functions remain on the DU side. This segmentation reduces the front haul bandwidth requirement from 2.4 Gbps to a much lower rate, as only essential control information needs to be transmitted between units.
Solution Approach 2:
The patent introduces a functional dimension to the C-RAN architecture by distributing different protocol layers to different physical units. Instead of concentrating all processing functions in one location (DU), the system distributes layer 1 functions to RU and layer 2 functions to DU, creating a multi-dimensional functional architecture that optimizes both centralized control and bandwidth efficiency.
2Quantity of substance
If layer 1 functions are distributed to the RU side, then front haul bandwidth is reduced, but processing complexity at the RU increases
Solution Approach 1:
The patent carefully segments layer 1 functions, placing only FFT, resource mapping, and physical channel generation on the RU side, while keeping more complex MAC layer functions on the DU side. This selective segmentation reduces RU processing complexity while still achieving bandwidth reduction goals.
Solution Approach 2:
The RU is equipped with self-service capabilities to perform local signal processing functions (FFT, resource mapping) without requiring constant DU intervention. This self-service approach reduces the processing burden on the DU and simplifies the overall system architecture while maintaining reduced front haul requirements.
3Loss of time
If more functions are implemented on the RU side, then latency is reduced, but device complexity and cost increase
Solution Approach 1:
The patent applies partial action by implementing only the essential layer 1 functions (FFT, resource mapping, physical channel generation) on the RU side, rather than all possible functions. This partial implementation achieves sufficient latency reduction for 5G requirements without unnecessarily increasing RU device complexity and cost.
Data Source
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AI summary
A base station is provided that includes an obtainer that obtains a first parameter used for generation of a signal of a physical downlink control format indicator channel, a second parameter used for generation of a signal of a physical downlink HARQ indicator channel, or a third parameter used for generation of a signal of a physical downlink control channel; a generator that generates the signal of the physical downlink control format indicator channel, the signal of the physical downlink HARQ indicator channel, or the signal of the physical downlink control channel using the first parameter, the second parameter, or the third parameter; and a transmitter that transmits the generated signal of the physical downlink control format indicator channel, the generated signal of the physical downlink HARQ indicator channel, or the generated signal of the physical downlink control channel.