Frequency Hopping via Cell ID and System Time
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Solution Overview
Problem
Current frequency hopping techniques in wireless communication networks, particularly in LTE, face challenges in maintaining efficient subband selection and mirroring functions, especially during HARQ transmissions, leading to performance degradation due to non-hopping scenarios and limited periodicity of hopping functions.
Innovation Solution
The proposed solution involves using both cell ID and system time information to extend the periodicity of the hopping function, allowing for synchronized subband selection and mirroring across multiple radio frames, ensuring frequency hopping in various operating scenarios by initializing a pseudo-random number generator with cell ID and system frame number, and generating PN sequences to determine subbands and mirroring based on these parameters.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If frequency hopping is performed using conventional techniques with limited periodicity, then implementation is simpler, but performance degrades due to non-hopping scenarios and resource fragmentation
Solution Approach 1:
The patent changes the parameters of the hopping function by extending its periodicity from conventional limited periodicity to at least two radio frames (40 ms). This is achieved by incorporating system time information (SFN) into the hopping function calculations, specifically using different offsets for different radio frames. This parameter change ensures frequency hopping occurs across HARQ transmissions while maintaining manageable complexity through standardized procedures.
Solution Approach 2:
The patent introduces dynamic behavior to the frequency hopping mechanism by making the hopping pattern adaptive to different radio frame structures and HARQ timing. The hopping function dynamically adjusts based on the radio frame number and HARQ process, allowing the system to optimize performance for different transmission scenarios while maintaining a unified framework that doesn't significantly increase implementation complexity.
2Reliability
If frequency hopping periodicity is extended to cover multiple radio frames, then resource fragmentation and collision are minimized, but synchronization and coordination become more complex
Solution Approach 1:
The patent implements periodic action by extending the hopping function periodicity to align with radio frame boundaries (at least two radio frames or 40 ms). This periodic structure ensures that frequency hopping occurs at predictable intervals across HARQ transmissions, reducing resource fragmentation while maintaining synchronization through the standardized radio frame timing already present in LTE systems.
Solution Approach 2:
The patent uses copying by reusing the existing radio frame number (SFN) and HARQ process identifiers to determine hopping patterns. Instead of introducing entirely new synchronization mechanisms, the system copies and leverages already-available timing information from the LTE framework, thereby extending hopping periodicity without proportionally increasing synchronization complexity.
3Adaptability or versatility
If frequency hopping is adapted for various HARQ transmission scenarios, then performance is maintained across different RTTs, but the hopping function becomes less predictable
Solution Approach 1:
The patent adapts the hopping function to various HARQ scenarios by changing parameters such as the radio frame offset and HARQ process index in the hopping calculations. This allows the same unified hopping function to generate appropriate frequency patterns for different RTTs (8 ms and 10 ms) and HARQ timing configurations, maintaining performance across scenarios while preserving predictability through deterministic parameter relationships.
Data Source
AI summary
Techniques for performing frequency hopping in a wireless network are described. In an aspect, frequency hopping may be performed based on both cell identity (ID) and system time information. In one design, a user equipment (UE) may determine a cell ID of a cell and may obtain system time information for the cell. The UE may determine resources to use for transmission with frequency hopping based on the cell ID and the system time information. In one design, the UE may initialize a PN generator in each radio frame with an initial value determined based on the cell ID and a system frame number (SFN) for the radio frame. The UE may determine the resources to use for transmission based on a hopping function, a mirroring function, and a PN sequence from the PN generator. The UE may send a transmission on the resources to the cell.