Reduced-Length OFDMA Map Messages for Overhead Reduction
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
OFDMA systems, such as those compliant with IEEE 802.16 standards, face significant per-frame overhead in transmitting resource allocation messages, particularly in narrow bandwidth systems, which impairs data throughput and efficiency.
Innovation Solution
Reduced-length downlink and uplink map messages are transmitted with modified headers and information elements, utilizing fewer bits for headers, CRC, and information elements, and eliminating unnecessary fields, thereby reducing the overall bandwidth required for MAC layer overhead.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If standard-length DLMAP and ULMAP messages are transmitted with full headers and information elements, then reliable resource allocation information is provided to all remote stations, but per-frame overhead bandwidth consumption increases significantly
Solution Approach 1:
The patent extracts and removes unnecessary or redundant fields from the standard DLMAP and ULMAP message structures. Specifically, it eliminates the GMAC header (32 bits) and reduces the CRC from 32 bits to 8 bits, while retaining only the essential information elements needed for resource allocation. This extraction of non-essential components reduces overhead bandwidth consumption while maintaining the reliability of critical resource allocation information.
Solution Approach 2:
The patent changes the parameter values of message structure components by reducing the header length from the standard 32 bits to a maximum of 16 bits, and reducing the CRC field from 32 bits to 8 bits. These parameter changes directly reduce the bandwidth consumption for overhead messages while preserving the essential functionality of reliable resource allocation communication.
2Reliability
If robust FEC Code is used for downlink MAP transmission to ensure all remote stations can receive it, then transmission reliability is improved, but the number of overhead slots required increases
Solution Approach 1:
The patent extracts and removes the GMAC header and full 32-bit CRC fields from the downlink MAP message, retaining only the essential information elements. By eliminating these redundant components, the message length is reduced, which directly reduces the number of overhead slots required for transmission while maintaining reliable delivery of critical resource allocation information through the retained essential fields.
3Ease of manufacture
If static bandwidth allocation is used for downlink MAP at every frame, then configuration simplicity is maintained, but bandwidth efficiency decreases when actual traffic is low
Solution Approach 1:
The patent introduces dynamic adaptation to the downlink MAP message structure by allowing the header length to vary up to a maximum of 16 bits and the CRC to be reduced to 8 bits based on actual traffic conditions. This dynamic approach allows the system to maintain configuration simplicity through defined constraints while improving bandwidth efficiency by adapting the message length to actual needs, avoiding the waste of static full-size allocation.
4Loss of information
If full-length headers and information elements are transmitted in MAP messages, then complete resource allocation information is provided, but data throughput is impaired due to increased overhead
Solution Approach 1:
The patent extracts and removes redundant information elements from the MAP messages, specifically eliminating the 32-bit GMAC header and reducing the 32-bit CRC to 8 bits. This extraction process reduces the overhead portion of the message while retaining all essential resource allocation information in the condensed header and information elements, thereby improving data throughput without sacrificing information completeness.
Solution Approach 2:
The patent changes the parameter values of message components by reducing the header length parameter to a maximum of 16 bits and the CRC parameter to 8 bits. These parameter changes reduce the overall message length and overhead proportion, which directly improves the ratio of useful data to overhead, thereby enhancing data throughput while maintaining complete resource allocation information through the optimized structure.
Data Source
AI summary
An OFDMA system having a reduced overhead, particularly suitable for narrow bandwidth systems, in which uplink and downlink map messages have reduced length for efficiency.