Frequency Hopping for Narrowband MTC Coverage
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Solution Overview
Problem
Current machine type communication (MTC) technologies face challenges in enhancing coverage for low-cost MTC user equipment, which can only transmit and receive data in narrow bandwidths, and require frequent repetitions due to limited frequency hopping gains, especially at high block error rates.
Innovation Solution
Implementing a frequency hopping method with parameters 'X', 'Y', and 'Z' for MTC user equipment, where 'X' is the duration of same physical resource block usage, 'Y' is the frequency hopping period based on channel estimation filter length, and 'Z' is a frequency hopping pattern indication, allowing for improved coverage by configuring frequency hopping patterns across subframes and system bandwidth.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If frequency hopping is implemented with narrow bandwidth for low-cost MTC user equipment, then device complexity is reduced, but coverage enhancement is limited and block error rates remain high
Solution Approach 1:
The frequency hopping process is segmented into multiple hops across different subframes, with each hop transmitting data over a narrow bandwidth. This segmentation allows low-cost devices to operate with simple narrowband transceivers while the cumulative effect of multiple hops across frequency provides diversity gain and coverage enhancement that would be unavailable with wideband transmission alone.
Solution Approach 2:
Frequency hopping employs periodic action by systematically transitioning between different frequency resources at defined intervals (hopping periods). The patent specifies hopping patterns where the transmission frequency changes periodically across subframes, creating time-frequency diversity that improves reliability without requiring complex continuous wideband processing in the device.
2Reliability
If frequency hopping is performed frequently to improve coverage, then reliability is improved, but the number of required repetitions increases and productivity decreases
Solution Approach 1:
The frequency hopping configuration is made dynamic and adaptable. The patent allows the hopping pattern, bandwidth, and resource allocation to be dynamically adjusted based on channel conditions, device capabilities, and network requirements. This dynamic approach optimizes the balance between coverage enhancement and transmission efficiency, avoiding excessive repetitions by adapting to real-time conditions.
Solution Approach 2:
Multiple frequency hopping parameters are introduced and optimized, including hopping bandwidth, hopping period, resource block allocation, and subframe configuration. By changing and optimizing these parameters, the system achieves effective coverage enhancement with a reduced number of repetitions compared to conventional approaches, improving overall productivity while maintaining reliability.
3Ease of manufacture
If narrow bandwidth is used for transmission to simplify device requirements, then ease of manufacture is improved, but frequency hopping gains are limited and reliability worsens
Solution Approach 1:
The patent transitions from a single-dimension (time-only or frequency-only) approach to a two-dimensional time-frequency hopping approach. By systematically hopping across both time (subframes) and frequency (resource blocks) dimensions, the system achieves diversity gain that compensates for the limited bandwidth, providing enhanced reliability without requiring complex wideband device implementation.
Solution Approach 2:
The frequency hopping mechanism serves multiple functions simultaneously: it provides coverage enhancement through diversity gain, enables efficient resource utilization across the spectrum, supports both uplink and downlink transmissions, and maintains compatibility with existing LTE infrastructure. This multi-functionality allows narrowband devices to achieve reliable communication without requiring device-specific wideband capabilities.
Data Source
AI summary
A method and apparatus may include receiving, by a machine type communication user equipment, parameters for frequency hopping in downlink or uplink. The parameters comprise an “X,”“Y,” and “Z” parameters, “X” corresponds to a duration for which the same physical resource blocks are used for transmission. “Y” corresponds to a frequency hopping period, and “Z” corresponds to a frequency hopping pattern indication. The method may also include performing frequency hopping in accordance with the parameters.