NLOS Wireless Backhaul Downlink With DFT-Spreading SC-FDMA
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Solution Overview
Problem
The increasing cell density in radio access networks leads to non-line-of-sight (NLOS) wireless backhaul channels, which require efficient communication mechanisms to manage higher traffic loads and maintain low latency and error rates, as traditional point-to-point line-of-sight wireless backhaul links become inadequate.
Innovation Solution
A method for NLOS wireless backhaul communication involving a radio frame with adjustable link directionality, employing time-frequency multiplexing, single carrier block transmission with Discrete Fourier Transform (DFT) spreading, and combining Single Carrier-Frequency Division Multiple Access (SC-FDMA) with Orthogonal Frequency Division Multiplexing (OFDM) to provide frequency diversity and low peak-to-average-power ratio (PAPR), along with Reed Solomon (RS) encoding and Turbo encoding for error correction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If cell density is increased to meet growing demand for voice and data services, then service capacity is improved, but traditional P2P LOS wireless backhaul communication mechanisms become inadequate
Solution Approach 1:
The patent segments the backhaul network from traditional P2P LOS architecture into a hierarchical P2MP NLOS architecture with one base station serving multiple remote units. This segmentation allows the system to handle increased traffic capacity while maintaining reliable communication through multiple path diversity and centralized coordination, resolving the contradiction between service capacity and communication reliability.
2Device complexity
If single carrier waveforms are used for P2P LOS transmission, then time-domain equalization is simplified, but the system cannot support increased cell density and NLOS conditions
Solution Approach 1:
The patent employs SC-FDMA which dynamically adapts to NLOS conditions while maintaining single carrier properties. The system dynamically adjusts resource allocation, modulation schemes, and coding rates based on channel conditions, allowing it to maintain low equalization complexity while achieving high adaptability to NLOS environments and increased cell density.
3Use of energy by moving object
If SC-FDMA is employed for downlink transmission, then peak-to-average-power ratio is reduced, but implementation complexity increases compared to traditional OFDM
Solution Approach 1:
The patent merges the advantages of SC-FDMA (low PAPR) with OFDM (efficient frequency multiplexing) in the downlink transmission. By combining single carrier modulation with frequency-domain resource allocation and DFT spreading, the system achieves both power amplifier efficiency and implementation feasibility, resolving the contradiction between energy efficiency and implementation complexity.
Data Source
AI summary
A method for communicating over a wireless backhaul channel comprising generating a radio frame comprising a plurality of time slots, wherein each time slot comprises a plurality of symbols in time and a plurality of sub-carriers in a system bandwidth, broadcasting a broadcast channel signal comprising a transmission schedule to a plurality of remote units in a number of consecutive sub-carriers centered about a direct current (DC) sub-carrier in at least one of the time slots in the radio frame regardless of the system bandwidth, and transmitting a downlink (DL) control channel signal and a DL data channel signal to a first of the remote units, wherein the DL data channel signal is transmitted by employing a single carrier block transmission scheme comprising a Discrete Fourier Transform (DFT) spreading for frequency diversity.