Satellite Air Interface Using Shared Forward and Dedicated Return Links
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Solution Overview
Problem
Satellite communication systems face challenges in establishing reliable communication links due to limited signal strength and geographical beam coverage, which affects the quality of service for wireless communication devices (WCDs) and requires optimized air interface protocols for forward and return links.
Innovation Solution
The method involves establishing a forward link using a shared frequency multiuser communication protocol with error correction applied to aggregated communications, and a return link with dedicated frequency assignments and non-slotted channel assignments, utilizing CDMA protocols like 1xEv-DO for efficient data multiplexing and error correction, and employing narrowband or wideband channels as needed.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a shared frequency multiuser communication protocol is used for the forward link, then bandwidth efficiency is improved, but signal strength and quality of service deteriorate due to limited satellite coverage area
Solution Approach 1:
The patent segments the communication system into multiple beams covering different geographical areas. Each beam is assigned to a specific WCD, allowing dedicated signal transmission paths that improve signal strength while maintaining bandwidth efficiency through the shared frequency protocol across multiple users within each beam coverage area.
2Productivity
If CDMA protocols with time-division multiplexed channels are used, then bandwidth efficiency is improved, but channel assignment complexity increases
Solution Approach 1:
The patent implements dynamic channel assignment where the base station can flexibly allocate time-division multiplexed channels to different WCDs based on real-time communication needs. This dynamic approach maintains bandwidth efficiency while managing complexity through intelligent control rather than rigid predetermined assignments.
3Reliability
If error correction codes are applied to aggregated communications, then reliability is improved, but processing time and complexity increase
Solution Approach 1:
The patent applies error correction codes to aggregated communications in advance, before transmission occurs. By pre-processing the error correction on aggregated data streams from multiple WCDs, the system improves reliability without adding significant processing time during the actual communication transmission phase.
4Reliability
If dedicated frequency assignments are used for return link channels, then signal quality is improved, but frequency spectrum utilization decreases
Solution Approach 1:
The patent applies dedicated frequency assignments selectively for return link channels serving specific WCDs in particular beam coverage areas. This localized approach provides improved signal quality for each WCD's return communication while the overall system maintains efficient frequency utilization through the shared forward link protocol and coordinated beam management.
Data Source
AI summary
A method is disclosed for establishing communication links in a satellite based wireless communication system. The method includes: establishing a forward link from the satellite to at least one of a plurality of subscriber wireless communication devices (WCDs) by use of a shared frequency multi-user communication protocol; applying an error correction code to use in the forward link, whereby the error correction applies to an aggregation of communications provided to multiple ones of the WCDs; and receiving communications in a return link signal by use of a protocol providing channels having dedicated frequency assignments and non-slotted channel assignment.