Orthogonal Coding for Dual-RAT Spectrum Sharing
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Solution Overview
Problem
In dual-connectivity arrangements for 4G LTE and 5G NR networks, operators face challenges in obtaining sufficient RF spectrum to separately define 4G and 5G carriers, making it impractical due to licensing costs and other issues.
Innovation Solution
The 4G and 5G access nodes are configured to operate on carriers that overlap in frequency, with orthogonal encoding used to differentiate their transmissions, allowing concurrent transmission on the same frequency, enabling the user equipment to decode each signal using specific orthogonal codes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If separate RF spectrum allocation is used for 4G and 5G carriers, then reliable dual-connectivity transmission is achieved, but spectrum requirements and licensing costs increase
Solution Approach 1:
The patent merges 4G LTE and 5G NR transmissions onto the same frequency band by using orthogonal coding schemes. The base station applies different orthogonal codes to 4G and 5G signals, allowing them to coexist on overlapping frequency resources without mutual interference, thus reducing the total RF spectrum required while maintaining reliable dual-connectivity transmission.
Solution Approach 2:
The patent changes the coding parameter of the transmitted signals by introducing orthogonal codes (such as Walsh-Hadamard codes) for 4G and 5G transmissions. This parameter change enables the signals to be distinguished at the receiver even when transmitted on the same frequency, resolving the contradiction between spectrum efficiency and transmission reliability.
2Quantity of substance
If orthogonal encoding is used for concurrent transmission on overlapping frequencies, then spectrum efficiency is improved, but signal decoding complexity increases
Solution Approach 1:
The patent applies orthogonal encoding at the transmitter side before signal transmission. The base station pre-multiples the 4G and 5G signals with orthogonal codes, so that when signals are combined on the same frequency, the receiver can simply correlate with the known orthogonal codes to separate them. This preliminary encoding action simplifies the receiver complexity compared to other multiplexing schemes.
Data Source
AI summary
A method and system for concurrent transmission of (i) a first bit sequence from a first access node to a UE and (ii) a second bit sequence from a second access node to the UE, when the first access node serves the UE on a first carrier according to a first radio access technology (RAT), the second access node serves the UE on a second carrier according to a second RAT, and the first and second carriers overlap in frequency. Per the disclosure, the access nodes could orthogonally encode their respective bit sequences and could concurrently transmit the resulting encoded bit sequences to the UE on the same frequency as each other.