NB-IoT Resource Element Utilization in Guard-Band Modes
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Solution Overview
Problem
In narrow band Internet of Things (NB-IoT) systems, resource waste occurs in guard-band and standalone modes due to unused resource elements (REs) reserved for the LTE system's physical downlink control channel and cell-specific reference signals, which are not utilized in the in-band mode, leading to inefficient resource allocation.
Innovation Solution
The proposed method optimizes resource utilization by repurposing idle REs in guard-band and standalone modes for transmitting signals, specifically using REs corresponding to OFDM symbols 0, 1, 2, 4, 7, 8, and 11 in subframes 0, 5, and 9, to carry information such as the Master Information Block (MIB-NB) and synchronization signals, thereby enhancing resource efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the first three OFDM symbols of subframes 0, 5, and 9 are reserved for LTE system's PDCCH and CRS in guard-band and standalone modes, then compatibility with LTE system is maintained, but resource utilization efficiency deteriorates due to idle REs
Solution Approach 1:
The patent makes the first three OFDM symbols of subframes 0, 5, and 9 serve multiple functions: they maintain LTE compatibility by reserving the structure for PDCCH and CRS, while simultaneously enabling NB-IoT transmission of synchronization signals (NPSS, NSSS) and master information block (MIB-NB). This multi-functionality resolves the contradiction by allowing the same time-frequency resources to support both LTE system requirements and NB-IoT resource utilization.
2Reliability
If REs at CRS locations are not used for MIB-NB transmission in in-band mode, then interference with LTE CRS is avoided, but resource utilization deteriorates due to unused REs
Solution Approach 1:
The patent applies different resource mapping strategies to different deployment modes. In in-band mode, REs at CRS locations are excluded from NB-IoT transmission to avoid interference. In guard-band and standalone modes, these same RE locations are actively used for NB-IoT synchronization signals and MIB-NB. This localized adaptation to different operational contexts resolves the contradiction by optimizing resource usage according to the specific deployment scenario.
Data Source
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AI summary
An information sending and receiving method and a device are disclosed, to reduce resource waste and improve resource utilization. The information sending method includes: generating, by a network device, a first signal; sending, on a first resource by the network device, the first signal to a terminal device. The first resource includes a first part of REs, the first part of REs includes at least one of the following REs: all REs corresponding to an OFDM symbol 0, an OFDM symbol 1, and an OFDM symbol 2 in each of a subframe 0, a subframe 5, and a subframe 9 of each radio frame on a first carrier; or an RE0, an RE3, an RE6, and an RE9 in each of an OFDM symbol 4, an OFDM symbol 7, an OFDM symbol 8, and an OFDM symbol 11 in the subframe 0 of each radio frame on the first carrier. The first carrier includes an anchor carrier in an NB-IoT or a non-anchor carrier in the NB-IoT.