PDCCH-less NB-IoT Data Transmission Reducing Control Overhead
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Solution Overview
Problem
Narrowband IoT (NB-IoT) and New Radio (NR) systems face large control overhead due to small packet transmissions, which reduces system capacity and efficiency, especially in applications with infrequent data traffic.
Innovation Solution
Implementing control-less data transmission methods such as PDCCH-less, PDCCH-lite, extremely compact DCI (E-DCI) formats, and direct data transmission over PDCCH, where NB-IoT/NR devices blindly decode data subframes or use reduced DCI overhead to transmit data without explicit scheduling information.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If explicit scheduling information is transmitted via PDCCH for each small packet, then reliable data transmission is achieved, but control channel overhead increases significantly
Solution Approach 1:
The patent extracts and removes the PDCCH scheduling information transmission for small packets in NB-IoT, allowing data to be transmitted without explicit control channel scheduling. This eliminates the control overhead while maintaining reliability through pre-configured uplink resources and simplified HARQ mechanisms.
Solution Approach 2:
The patent segments the control signaling by separating small packet transmissions from regular LTE scheduling. Small packets use a dedicated simplified uplink grant mechanism with pre-configured parameters, while larger packets continue to use standard PDCCH scheduling, thus reducing overall control overhead for IoT applications.
2Productivity
If control-less transmission is implemented to reduce overhead, then system capacity increases, but blind decoding complexity at UE increases
Solution Approach 1:
The patent applies preliminary action by pre-configuring uplink resources, transmission parameters, and HARQ settings through RRC signaling before data transmission. This allows the UE to directly transmit small packets without real-time PDCCH scheduling, reducing blind decoding requirements while maintaining system capacity.
Solution Approach 2:
The patent changes key transmission parameters for small packets, including fixed transport block sizes, predetermined modulation schemes, and simplified resource allocation. These parameter changes reduce the search space for blind decoding while enabling efficient control-less transmission for NB-IoT devices.
3Adaptability or versatility
If traditional PDCCH scheduling is used for small packets, then dynamic resource allocation is achieved, but transmission efficiency decreases due to overhead
Solution Approach 1:
The patent introduces dynamic grant-free access where UEs can transmit small packets without PDCCH scheduling, with the base station dynamically allocating resources through pre-configuration and handling collisions through randomized access protocols. This maintains adaptability while improving efficiency for small packet transmissions.
Data Source
AI summary
Various methods of control-less data transmission for NB-IoT/NR devices have been proposed to improve efficiency and system capacity in cellular networks. In a first embodiment, a PDCCH-less operation is performed between eNB and UE. UE will blindly decode some PDSCH subframes according to the parameters configured by higher layer. In a second embodiment, a PDCCH-lite operation is performed between eNB and UE. UE may use one PDCCH to schedule more than one subsequent PDSCH resources. In a third embodiment, an extremely compact DCI (E-DCI) format is used between eNB and UE. When the same assignment parameters are used by the eNB for the UE, DCI overhead may be reduced by E-DCI. In a fourth embodiment, direct data transmission in PDCCH is performed between eNB and UE. Data transmission is directly transmitted by PDCCH with a new DCI format.