Narrowband TDD Frame Structure for Reliable Deep Indoor Transmission
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Solution Overview
Problem
Narrowband communication systems face challenges in ensuring reliable transmission to challenging locations due to limited frequency bandwidth, leading to increased chances of transmission failures, particularly in deep indoor environments, where existing frame structures may not adequately support repeated transmissions.
Innovation Solution
The implementation of a narrowband time-division duplex (TDD) frame structure that includes multiple contiguous downlink and uplink subframes, allowing for repeated transmissions and flexible subframe configurations to enhance transmission reliability, specifically designed for narrowband communications like NB-IoT and eMTC.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If narrowband communication is used to reduce device complexity and extend battery life, then device complexity and energy consumption are improved, but transmission reliability deteriorates in challenging locations
Solution Approach 1:
The patent implements repeated transmissions of the same data across multiple subframes in a periodic manner. The TDD frame structure allocates multiple downlink subframes (e.g., subframes 0, 1, 2, 4, 5, 6, 8, 9) that can carry repeated transmissions of NB-IoT data, allowing the receiver to combine multiple copies and improve decoding reliability in challenging locations while maintaining narrowband operation.
2Reliability
If repeated transmissions are implemented to improve transmission reliability, then transmission reliability is improved, but transmission time increases
Solution Approach 1:
The patent introduces flexible subframe configurations that can be dynamically adjusted based on channel conditions and traffic requirements. The TDD frame structure allows certain subframes to be configured as downlink, uplink, or flexible subframes, enabling the system to optimize the number of repeated transmissions needed while minimizing transmission time. This dynamic configuration allows the system to adapt to varying reliability requirements without always using the maximum number of repetitions.
3Reliability
If TDD frame structure is used to support repeated transmissions, then transmission reliability is improved, but frame structure complexity increases
Solution Approach 1:
The patent designs the TDD frame structure to serve multiple functions simultaneously. The same frame structure supports both repeated transmissions for reliability improvement and flexible configuration for adapting to different traffic patterns and channel conditions. The flexible subframes can be configured as downlink or uplink based on needs, allowing the system to use the same infrastructure for multiple purposes without requiring separate specialized structures.
Data Source
AI summary
A UE may determine a frame structure for narrowband communications, the frame structure corresponding to one frame structure from a group of TDD frame structures of different downlink and uplink subframe configurations. The UE receives configuration information indicating a first carrier to monitor for a BCH and/or a SIB1. Then, the UE receives a PSS, an SSS, and the BCH and/or the SIB1 using the frame structure determined for the narrowband communications. The first carrier that is used to receive the BCH and/or the SIB1 may be different from a second carrier used to receive one or more of the PSS or the SSS.