DOCSIS Wireless Hub Transceiver Extends Cable Modem Service
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Solution Overview
Problem
Current MMDS networks face limitations due to limited radio frequency spectrum, high costs for licensed channels, and the need for expensive diplexers, making it difficult for CATV providers to offer services to areas without direct coax cable connections.
Innovation Solution
A wireless link system that extends DOCSIS cable modem service using a wireless hub transceiver connected to a distribution coax cable, allowing downstream and upstream data transmission over unlicensed 5 GHz bands, eliminating the need for additional transmission licenses and reducing equipment costs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If MMDS wireless cable is used to deliver data services to areas without coax cable connections, then service coverage is extended, but the cost of equipment including diplexer increases
Solution Approach 1:
The patent extracts the diplexer requirement by separating upstream and downstream transmissions into different time slots rather than different frequency channels. The wireless cable modem transmits upstream data in reverse direction time slots while receiving downstream data in forward direction time slots, eliminating the need for frequency separation hardware like diplexers at subscriber locations.
Solution Approach 2:
The wireless cable modem is designed to handle both upstream and downstream communications using a single antenna and transceiver unit. The modem performs multiple functions including receiving downstream packets, transmitting upstream packets, and managing time slot allocation, replacing the need for separate diplexer, upstream amplifier, and downstream amplifier components.
2Reliability
If licensed MMDS channels are used for wireless transmission, then reliable communication is achieved, but the cost of license acquisition increases
Solution Approach 1:
The patent uses unlicensed ISM bands (2.4 GHz, 5.8 GHz) as an intermediary frequency range instead of licensed MMDS bands. These unlicensed bands serve as a mediator that provides sufficient bandwidth for wireless cable transmission without requiring expensive frequency licenses, while still maintaining reliable communication through proper modulation and error correction techniques.
3Device complexity
If 6 MHz television channels are used for upstream and downstream transmission, then frequency allocation is simplified, but the number of available channels decreases
Solution Approach 1:
The patent implements dynamic time slot allocation where the wireless cable modem dynamically assigns different time slots for upstream and downstream transmissions based on traffic requirements. Instead of fixed frequency channels, the system dynamically switches between forward direction (downstream) and reverse direction (upstream) time slots, increasing channel utilization efficiency and reducing the number of physical channels needed.
Solution Approach 2:
The wireless cable modem uses periodic time-division multiplexing where upstream and downstream transmissions occur in alternating periodic time slots. The modem periodically switches between receiving mode (downstream) and transmitting mode (upstream), allowing single-frequency operation while supporting bidirectional communication. This periodic action maximizes the use of available spectrum by ensuring that each frequency is fully utilized in both directions over time.
Data Source
AI summary
An apparatus and method are presented to allow the extension of a DOCSIS cable modem service over a wireless link. According to the invention a wireless hub transceiver is connected to a distribution coax cable of a DOCSIS based system. The downstream data are transferred over a wireless link to a remote subscriber radio frequency (RF) unit connected to a cable modem that provides the downstream data to the subscriber. Similarly, upstream data are sent from the subscriber cable modem over the wireless link to the wireless hub transceiver where such data are inserted back to the distribution coax cable.