Short TTI Control Channel Allocation in LTE
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Solution Overview
Problem
The LTE system only supports transmission time intervals (TTIs) of 1 millisecond, limiting the ability to transmit control and data channels at shorter intervals, which can lead to inefficiencies in resource allocation and data processing.
Innovation Solution
A method and apparatus for transmitting and receiving data using short transmission time intervals (sTTIs) by configuring control channels in short resource block sets (sRBS) and short control channel elements (sCCE), allowing for data reception in a slot unit or subslot unit, with the use of a resource expansion field and control resource reuse field to optimize data channel allocation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the LTE system uses a fixed 1ms TTI for all transmissions, then the system maintains simplicity in resource allocation and control channel design, but the system cannot achieve efficient data transmission at shorter intervals, leading to increased latency and reduced responsiveness
Solution Approach 1:
The patent segments the 1ms subframe into multiple shorter TTI units (e.g., 2ms, 1ms, 0.5ms, or shorter) to enable flexible transmission time intervals. This segmentation allows the system to allocate resources in smaller, more granular time units, improving data transmission efficiency and reducing latency while maintaining manageable complexity through structured resource block sets (sRBS) and control channel elements (sCCE)
Solution Approach 2:
The patent introduces dynamic TTI length adjustment, where the TTI duration can be changed based on traffic conditions and service requirements. The system can dynamically select different TTI lengths (shorter or longer than 1ms) and configure相应的 control channels and resource blocks, enabling adaptive resource allocation that improves productivity without requiring complete system redesign
2Productivity
If the system allocates control channels and data channels in 1ms subframe units, then the resource allocation structure remains simple and standardized, but the system cannot achieve finer-grained resource allocation, resulting in resource wastage and reduced spectral efficiency
Solution Approach 1:
The patent divides the traditional 1ms subframe-based resource allocation into shorter TTI-based resource block sets (sRBS). Each sRBS contains control channels (sPDCCH) and data channels (sPDSCH/sPUSCH) that can be independently allocated and managed. This segmentation enables finer-grained resource allocation, improving resource utilization efficiency while the structured organization of sRBS and sCCE keeps the configuration complexity manageable
Solution Approach 2:
The patent introduces a new dimension of resource allocation by creating parallel control channel structures (sPDCCH in sRBS) that operate independently from the legacy PDCCH in regular subframes. This dimensional separation allows the system to allocate control and data resources in shorter time units without disrupting the existing 1ms subframe structure, thereby improving resource allocation efficiency while maintaining backward compatibility and limiting complexity increase
3Productivity
If the system uses legacy control channels for short TTI data transmission, then the control channel design remains simple and reusable, but the control channels cannot be efficiently allocated to multiple terminals in short time intervals, leading to control overhead and reduced system capacity
Solution Approach 1:
The patent segments the control channel resources by creating short control channel elements (sCCE) within short resource block sets (sRBS). Each sCCE can be independently allocated to different terminals for short TTI transmissions. This segmentation enables multiple terminals to be served in parallel within the same subframe, improving control channel allocation efficiency and system capacity while the modular sCCE structure keeps resource management complexity manageable
Solution Approach 2:
The patent designs the sPDCCH and sCCE structures to be universal and reusable across different TTI lengths and service types. The same control channel framework can serve multiple terminals with different requirements (e.g., different TTI durations, different data rates) without requiring separate dedicated control channels for each case. This universality improves allocation efficiency and system capacity while avoiding the complexity of managing multiple specialized control channel designs
Data Source
AI summary
Disclosed are a method and an apparatus for receiving data by decoding a control channel received in unit of a short transmission time interval (sTTI); and receiving, if a first control channel matched with the terminal is determined based on the decoding result, data in a short resource block set (sRBS) including the first control channel.