DVB-SH Uplink Signaling via OFDM Watermarking
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Solution Overview
Problem
In DVB-SH single-frequency networks, existing technologies lack a cost-effective method to identify and utilize uplink-capable CGC earth stations, leading to inefficiencies in providing interactive and messaging services, as they are limited to downlink operations without provisions for uplink channels.
Innovation Solution
Reserving specific code words in the DVB-SH data frame to indicate uplink availability, allowing CGC earth stations with uplinks to transmit unique signaling messages while non-uplink stations transmit dummy sequences, minimizing interference and enabling terminals to identify uplink-capable stations without requiring additional hardware or receivers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If watermark embedding at content level is used to identify individual transmitters, then transmitter identification is achieved, but it cannot be applied in SFN networks where all transmitters must transmit identical signals
Solution Approach 1:
The patent moves the identification mechanism from the content dimension to the physical layer dimension by embedding watermark sequences in the OFDM signal structure (subcarrier positions, time positions, or code divisions) rather than in the broadcast content, enabling transmitter identification while maintaining signal identity requirements for SFN operation
Solution Approach 2:
The patent introduces watermark sequences as an intermediary layer between the physical signal and the broadcast content, allowing transmitter identification without modifying the actual content being transmitted, thus maintaining SFN compatibility while enabling identification
2Measurement precision
If watermark sequence is embedded in physical layer to identify transmitters, then transmitter identification is enabled in SFN network, but network performance degradation occurs due to interference between watermarked signals
Solution Approach 1:
The patent applies watermarking locally to specific components of the OFDM signal (specific subcarriers, time positions, or code divisions) rather than across the entire signal, minimizing interference impact on the overall network performance while maintaining identification capability
Solution Approach 2:
The patent combines multiple watermarking techniques (spatial, temporal, and frequency domain watermarking) into a composite approach, allowing flexible selection and combination of methods based on specific network conditions to balance identification accuracy with performance maintenance
3Loss of information
If trial and error protocol is used for CGC identification, then uplink availability can be determined, but unnecessary battery consumption and transmission delays occur
Solution Approach 1:
The patent enables terminals to proactively identify uplink-capable CGC earth stations through watermark detection before attempting uplink transmission, eliminating the need for trial-and-error protocols and reducing both battery consumption and transmission delays
4Measurement precision
If watermark embedding is applied at radio frequency level in DVB-SH signal, then transmitter identification is achieved, but downward compatibility is compromised and terminal costs increase due to required hardware upgrades
Solution Approach 1:
The patent designs the watermark embedding approach to be universally compatible with existing DVB-SH terminal hardware by operating within the existing signal processing chain, allowing the same hardware to serve both traditional DVB-SH reception and watermark detection functions without requiring separate receivers or hardware upgrades
Data Source
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AI summary
The method for transmitting user data signals in a communication network is particularly suitable for a communication network equipped with at least one first ground station, at least one second ground station, and several terminals, wherein the first and second ground stations transmit received user data to the terminals, and the at least one second ground station is capable of receiving user data from a terminal and forwarding it (i.e., the second ground station is uplink-capable). In this method, the first and second ground stations receive essentially identical user data simultaneously and transmit it to the terminals.In this process, only the at least one second ground station transmits, in addition to the user data it supplies to the terminals, configuration data that can be processed by these terminals. This configuration data signals to a terminal receiving user data from the at least one second ground station that the at least one second ground station can potentially receive and forward user data sent by that terminal.