TDM Frame Time-Frequency Slicing for Capacity Utilization
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Solution Overview
Problem
Digital broadband broadcast networks face inefficiencies in transmission capacity utilization due to fixed bit rates in time-division multiplexing (TDM) systems, leading to wasted capacity and limited service provision.
Innovation Solution
The implementation of time-frequency (TF) slicing, where a TDM frame is divided into subframes and slots, allowing for dynamic time shifting and cyclic shifting of slots, enabling more efficient use of transmission capacity by averaging bit rate variations across multiple RF channels.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If TDM capacity is reserved according to maximum bit rate to guarantee stream fit, then reliability is improved, but transmission capacity utilization deteriorates due to wasted slots
Solution Approach 1:
The patent applies dynamics by enabling variable bit rate allocation within TDM slots through time-frequency slicing. Instead of fixed slot reservations, the system dynamically adjusts the amount of capacity allocated to each service based on actual bit rate needs, allowing slots to be flexibly divided and reassigned. This resolves the contradiction by maintaining reliability through guaranteed minimum allocations while improving capacity utilization by eliminating wasted space through dynamic adjustment.
Solution Approach 2:
The system changes the parameter of bit rate allocation from fixed to variable within the TDM framework. By introducing time-frequency slicing, the patent enables the bit rate assigned to each service to vary over time and frequency, allowing the system to adapt to actual traffic demands. This parameter change allows the system to guarantee minimum service levels while utilizing remaining capacity for additional services, thereby resolving the contradiction between reliability and capacity efficiency.
2Device complexity
If fixed bit rate TDM is used, then device complexity is reduced, but adaptability deteriorates due to inability to handle variable bit rate services efficiently
Solution Approach 1:
The patent segments the TDM frame into multiple subframes and further divides subframes into slots that can be independently allocated. This segmentation allows the system to maintain the simple fixed TDM structure at the frame level while introducing flexibility at the subframe and slot levels. By dividing the transmission structure into hierarchical segments, the system achieves adaptability for variable bit rate services without fundamentally complicating the overall TDM device architecture.
Solution Approach 2:
The patent introduces a time-frequency dimension to the traditional time-division multiplexing by creating time-frequency slices. This dimensional extension allows services to be allocated not only in time slots but also across frequency resources within each slot. This additional dimension provides the adaptability needed for variable bit rate services while building upon the existing TDM framework, thus improving versatility without proportionally increasing device complexity.
3Productivity
If more services are provided in TDM slots, then productivity increases, but bit rate variation increases leading to more capacity waste
Solution Approach 1:
The patent applies parameter changes by enabling variable bit rate allocation across multiple services within the same TDM frame structure. Through time-frequency slicing, each service can have its bit rate parameter adjusted independently based on actual demand, allowing more services to be accommodated without proportionally increasing overall bit rate variation. This dynamic parameter adjustment reduces capacity waste while supporting higher service density.
Solution Approach 2:
The patent merges multiple services into shared time-frequency resources through slicing. Instead of dedicating fixed slots to each service, the system combines multiple services into flexible slices that can be dynamically allocated. This merging approach allows more services to share the available capacity efficiently, reducing the bit rate variation penalty that would occur with separate fixed allocations, thereby increasing productivity while minimizing capacity waste.
Data Source
AI summary
A system and method for dynamically dividing the capacity of a fixed time division multiplexing (TDM) frame between physical channels for data transmission. According to various embodiments, a time frequency frame is divided into a plurality of subframes, and each of the plurality of subframes are divided into a plurality of corresponding slots. The plurality of slots are then selectively time shifted such that a defined time shift exists between corresponding slots in each subframe within the time frequency frame. For any slots or slot portions which have been selectively shifted beyond the end of the time frequency frame, such slots or slot portions are cyclically shifted to the beginning of the frame. Service data is then written into the slots of the time frequency frame, and the frame containing the service data can then be transmitted. Initialization and service access processes for a receiver are also provided.