NLOS Wireless Backhaul Downlink Using DFT-Spread 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 new 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 network capacity and coverage are improved, but traditional P2P LOS wireless backhaul communication mechanisms become inadequate due to NLOS conditions
Solution Approach 1:
The patent segments the backhaul communication into multiple remote units (RUs) that can be individually managed and configured. Each RU can operate independently with its own SC-FDMA parameters, allowing the system to handle NLOS conditions for specific units without affecting the entire network. This segmentation enables gradual deployment and optimization as cell density increases.
Solution Approach 2:
The patent changes key communication parameters by adopting SC-FDMA with configurable cyclic prefix lengths, subcarrier spacings, and resource block allocations. These parameter changes allow the system to adapt to NLOS channel conditions while maintaining reliability, resolving the contradiction between increased network capacity and backhaul communication reliability.
2Reliability
If SC-FDMA is employed for NLOS wireless backhaul communication, then bit error rate is reduced and frequency diversity is achieved, but system complexity increases due to DFT spreading and time-frequency multiplexing
Solution Approach 1:
The patent makes the base station and remote units multi-functional by implementing both SC-FDMA and OFDM capabilities within the same system architecture. This universality allows the system to use SC-FDMA for reliable NLOS communication while maintaining the option to use OFDM for other scenarios, managing complexity through flexible, multi-purpose equipment design.
Solution Approach 2:
The patent introduces dynamic configuration of SC-FDMA parameters including variable cyclic prefix lengths, adjustable subcarrier spacings, and flexible resource block allocations. This dynamics allows the system to optimize performance for specific NLOS conditions while managing complexity through adaptive rather than fixed configurations, reducing the burden on system design.
3Productivity
If adjustable link directionality ratio is implemented for traffic load balancing, then uplink and downlink traffic efficiency are improved, but radio frame structure complexity increases
Solution Approach 1:
The patent implements a dynamic link directionality ratio that can be adjusted based on traffic conditions. The radio frame structure includes configurable uplink and downlink time slots with flexible proportions, allowing the system to optimize traffic load balancing in real-time while managing complexity through standardized frame templates that can be reconfigured without complete redesign.
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.