OFDM IQ Sample Prediction Coding for Fronthaul Bandwidth Limits
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Solution Overview
Problem
The high-speed transport requirements of fronthaul links in distributed base station systems, particularly for 5G networks, lead to increased costs and energy consumption due to the need for numerous high-speed links, which can bottleneck transmission capacity and jeopardize the feasibility of centralized radio access networks.
Innovation Solution
A method and apparatus that compress IQ samples by converting a second number of IQ samples into prediction errors using a predictive filter, allowing for reduced bit transmission over the fronthaul link while maintaining compliance with relevant radio standards, by transmitting un-coded or minimally coded IQ samples at the boundary between OFDM symbols and encoding prediction errors with fewer bits.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If IQ samples are transmitted over fronthaul links in distributed base station systems, then radio coverage and throughput are improved, but transmission capacity becomes bottlenecked and energy consumption increases
Solution Approach 1:
The patent extracts and transmits only the essential information from IQ samples by converting them to prediction errors. Instead of transmitting the full IQ samples, the system extracts the difference between actual and predicted values, which contains the critical information while occupying minimal bandwidth and energy resources.
Solution Approach 2:
The patent changes the representation parameter of IQ samples from raw amplitude-phase values to prediction errors. This parameter transformation reduces the dynamic range and variability of transmitted data, allowing for more efficient compression and lower energy consumption during transmission while preserving the essential signal characteristics.
2Speed
If high-speed links are deployed to meet fronthaul transport requirements, then transmission capacity is increased, but cost increases dramatically
Solution Approach 1:
The patent extracts only the necessary information from IQ samples by using prediction error coding. This extraction approach allows the system to maintain high effective transmission speed for critical data while using lower-cost, lower-capacity physical links, thereby dramatically reducing the quantity and cost of high-speed transmission infrastructure required.
Solution Approach 2:
The patent creates a compressed representation (copy) of the original IQ samples in the form of prediction errors. This copy contains the essential signal information but occupies minimal space, allowing transmission over cheaper, lower-bandwidth links while maintaining the fidelity needed for high-speed communication performance.
3Quantity of substance
If data compression is applied to IQ samples, then fronthaul bandwidth is reduced, but maintaining compliance with radio standards becomes challenging
Solution Approach 1:
The patent implements a feedback mechanism where the receiver uses the transmitted prediction errors to reconstruct IQ samples and generate new predictions for the next block. This feedback loop ensures that the compressed data maintains the statistical properties and timing characteristics required by radio standards, thereby ensuring compliance while achieving significant compression.
Solution Approach 2:
The patent performs preliminary prediction of IQ samples before transmission, creating prediction errors that inherently encode the signal characteristics. This preliminary action prepares the data in a form that is both highly compressible and guaranteed to maintain compliance with radio standards during reconstruction, as the prediction model is designed to preserve essential signal properties.
Data Source
AI summary
Described is a method performed by an encoder of a base station system (100) of a wireless communication network, for handling a bit stream for transmission over a transmission link (165) between a remote unit (160) and a base unit (170) of the base station system. The remote unit is arranged to transmit wireless signals to and receive from mobile stations (180). The bit stream comprises a first OFDM symbol and a second OFDM symbol, each OFDM symbol comprising a number of consecutive IQ samples. The method comprises, for a first number of the IQ samples situated at a boundary between the first and the second OFDM symbol, transmitting, over the transmission link to a decoder of the base station system, the first number of IQ samples having a representation spanning a first amplitude range. The method further comprises, for a second number of IQ samples of the second OFDM symbol, following the first number of IQ samples, converting, using a predictive filter, individual of the second number of IQ samples to IQ prediction errors, where the IQ prediction errors have a representation spanning a second amplitude range that is smaller than the first amplitude range, and transmitting the IQ prediction errors over the transmission link to the decoder.