Reference Signal Bandwidth Determination in Narrowband Wireless Systems
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Solution Overview
Problem
In wireless communication systems, particularly in narrowband systems like eMTC and NB-IoT, there is ambiguity regarding the presence and bandwidth of reference signals (RS) in subframes, which can lead to interference and power savings issues due to differing configurations for different types of user equipment (UEs).
Innovation Solution
The techniques involve determining and signaling the presence and bandwidth of RS in subframes, with the base station (BS) transmitting RS in a determined bandwidth and UEs monitoring for RS based on this determination, using standardized signaling to clarify RS presence and bandwidth, especially in cases where RS are transmitted at wider bandwidths than nominal narrowband channels.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If reference signals are transmitted at wider bandwidths than nominal narrowband channels to support different types of UEs, then adaptability and versatility are improved, but ambiguity arises regarding RS presence and bandwidth configuration
Solution Approach 1:
The patent implements dynamic RS bandwidth configuration where the base station can transmit reference signals at flexible bandwidths (e.g., 1.08 MHz, 3.24 MHz, or system bandwidth) depending on UE type and network conditions. The bandwidth is adjusted dynamically rather than being fixed, allowing the system to adapt to different scenarios while maintaining clear signaling about the actual bandwidth being used.
Solution Approach 2:
The patent introduces an intermediary signaling mechanism (e.g., DCI format, RRC configuration, or system information blocks) that explicitly conveys RS presence and bandwidth information from the base station to UEs. This intermediary signal resolves the ambiguity by providing a clear indication of the actual RS configuration, allowing UEs to correctly interpret whether RS are present and at what bandwidth.
2Adaptability or versatility
If different bandwidth configurations are used for different UE types, then adaptability is improved, but device complexity increases due to multiple configuration scenarios
Solution Approach 1:
The patent creates a universal RS transmission framework that can serve multiple UE types (narrowband IoT UEs, eMTC UEs, LTE UEs, NR UEs) through a single configurable system. The base station uses a unified configuration mechanism that can adapt to different UE capabilities, allowing one system to perform multiple functions rather than requiring separate configurations for each UE type.
Solution Approach 2:
The patent manages complexity by dynamically changing key parameters (bandwidth, presence indication, frequency location) based on UE type and network conditions. Instead of maintaining separate fixed configurations for different UE types, the system changes parameters as needed, simplifying the overall configuration management while maintaining support for diverse UE capabilities.
3Measurement precision
If reference signal bandwidth is increased to support wider channel monitoring, then measurement precision is improved, but use of energy increases due to extended monitoring requirements
Solution Approach 1:
The patent applies partial action by allowing UEs to monitor only the necessary portion of the bandwidth based on their capabilities and current needs. Narrowband UEs monitor only their narrowband region, while wider-capability UEs can monitor broader bandwidths when needed. This partial monitoring approach provides sufficient measurement precision for each UE type without requiring all UEs to continuously monitor the full bandwidth, thus reducing overall energy consumption.
Data Source
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AI summary
Aspects of the present disclosure provide techniques and apparatus for determining presence and/or bandwidth of reference signals (RS) in systems that utilize narrowband regions of wider system bandwidth for wireless communications, such as enhanced machine type communication(s) (eMTC) systems and/or narrowband Internet-of-Things (NB-IoT) systems. Aspects provide a method for wireless communications by a user equipment (UE) operating in a narrowband region of a wider system bandwidth. The method generally includes determining at least one of: a presence of one or more RS in a subframe or a bandwidth of the one or more RS, wherein the bandwidth of the one or more RS is greater than or equal to a bandwidth of the narrowband region; and monitoring for the one or more RS in the subframe based on the determination.