Coherent RoF Transceiver for 5G Fronthaul Bandwidth Efficiency
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Solution Overview
Problem
Conventional CPRI-based fronthaul networks in radio access networks face significant overhead and economic impracticality for 5G applications, failing to provide sufficient data throughput and network capacity to meet the increasing demands of 5G channel bands and high-bandwidth applications.
Innovation Solution
The implementation of radio-over-fiber (RoF) optical transport systems, which use coherent RoF transceivers to modulate and demodulate digital wireless signals onto optical digital subcarrier (ODS) signals, enabling efficient transmission over optical fibers between remote radio heads (RRHs) and baseband units (BBUs, thereby reducing the need for multiple fibers and increasing bandwidth efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If CPRI-based fronthaul networks are used, then wireless network access can be provided, but significant overhead limits data throughput efficiency and economic feasibility
Solution Approach 1:
The patent extracts and removes the CPRI protocol overhead from the fronthaul transmission system. By using direct optical modulation of RF signals instead of CPRI encapsulation, the system eliminates protocol headers, synchronization overhead, and management data that constitute the significant overhead in CPRI-based systems, thereby improving data throughput efficiency.
Solution Approach 2:
The patent replaces the electrical/protocol-based CPRI processing system with an optical modulation system. Instead of using CPRI protocol encapsulation and electrical signal processing, the system directly modulates RF signals onto optical carriers using optical modulators, substituting the mechanical/electrical protocol processing with optical domain operations that have lower overhead.
2Productivity
If multiple fibers are used to support high bandwidth, then data capacity increases, but equipment costs increase
Solution Approach 1:
The patent makes existing optical fiber infrastructure multi-functional by enabling it to carry both traditional data traffic and high-bandwidth 5G fronthaul traffic simultaneously. The direct optical modulation technique allows the same fiber infrastructure to support multiple functions without requiring dedicated high-capacity fibers, thereby reducing the need for additional fiber deployments and associated equipment costs.
Solution Approach 2:
The patent changes the modulation parameters of the optical signals to achieve higher spectral efficiency. By using advanced modulation schemes and direct RF-to-optical modulation, the system increases the amount of data that can be transmitted over existing fibers without changing the physical infrastructure, thereby avoiding the cost of deploying additional fibers or upgrading equipment.
3Length of stationary object
If optical fiber connections are used, then transmission distance increases, but bandwidth efficiency decreases due to CPRI overhead
Solution Approach 1:
The patent replaces the CPRI protocol processing system with direct optical modulation. Instead of encoding RF signals into CPRI frames with extensive overhead and then transmitting over electrical interfaces followed by optical conversion, the system directly modulates RF signals onto optical carriers, eliminating the intermediate electrical processing steps and their associated overhead, thereby improving bandwidth efficiency while maintaining long transmission distances.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach significantly enhances bandwidth efficiency, reduces equipment costs, and maintains signal integrity for 5G mm-wave channel bands, allowing a single wavelength to support high-capacity 5G MIMO antennas, making it economically and technically feasible for 5G fronthaul networks.
Implementation Method 1
modulating the incoming digital wireless signals onto first serial streams of optical digital subcarrier (ODS) signals in the frequency domain, wherein the modulating includes phase modulation of at least one polarization component in the optical domain
Implementation Method 2
modulating the incoming digital wireless signals onto first serial streams of optical digital subcarrier (ODS) signals in the frequency domain, wherein the modulating includes phase modulation of at least one polarization component in the optical domain
Implementation Method 3
transmitting the first serial streams of ODS signals via an optical fiber to the BBU
Implementation Method 4
demodulating the incoming digital wireless signals from the first serial streams of ODS signals
Data Source
AI summary
A method and system for bandwidth efficient optical transport in radio access networks using radio-over-fiber optical transport may directly transmit radio access signals over an optical fiber by frequency multiplexing multiple parallel streams of digital wireless signals into a serial stream of optical digital subcarrier signals. A radio-over-fiber transceiver to enable efficient optical transport in radio access networks may be implemented on remote radio head and baseband unit equipment as a plug-in digital coherent optics module or as an on-board internally mounted digital coherent optics module.