SC-FDMA Frequency Hopping via Cyclic Shift and Mirror Transposition
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Solution Overview
Problem
Conventional frequency hopping techniques in single carrier frequency division multiple access (SC-FDMA) systems face challenges in preserving single carrier constraints, leading to increased peak to average power ratio (PAPR) and interference, especially when data blocks span the centerline of the frequency spectrum.
Innovation Solution
The method involves dividing a transmission allocation unit into time-based slots with frequency sub-divisions, allowing for cyclic shift or mirror transposition of user data across these slots while maintaining contiguous tone assignments, thereby reducing interference and preserving low PAPR.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If frequency hopping is implemented in SC-FDMA systems, then interference is reduced, but single carrier constraints are violated leading to increased PAPR
Solution Approach 1:
The transmission allocation unit is divided into multiple time-based slots, each containing frequency sub-divisions. User data is segmented and allocated to different frequency sub-divisions across time slots, enabling frequency hopping while maintaining contiguous tone assignments within each slot to preserve single carrier properties and low PAPR.
Solution Approach 2:
The system dynamically shifts frequency allocations of user data across time slots through cyclic frequency shifting or mirror transposition. This dynamic frequency hopping reduces interference while the contiguous tone assignment constraint within each slot is maintained to preserve low PAPR characteristics.
2Adaptability or versatility
If data blocks span the centerline of the frequency spectrum, then frequency diversity is improved, but interference increases and single carrier constraints are compromised
Solution Approach 1:
Mirror transposition frequency shifting reflects frequency sub-divisions across the centerline of the frequency spectrum in an asymmetric manner. This creates frequency diversity by spanning the centerline while maintaining contiguous tone assignments, thereby avoiding interference issues associated with conventional symmetric frequency hopping.
3Object-affected harmful factors
If conventional frequency hopping is applied, then interference reduction is achieved, but PAPR increases due to violation of single carrier constraints
Solution Approach 1:
By segmenting the transmission into time-based slots with frequency sub-divisions and maintaining contiguous tone assignments within each slot, the system preserves single carrier properties and low PAPR while still achieving frequency hopping across slots to reduce interference.
Solution Approach 2:
Dynamic frequency shifting through cyclic shifts or mirror transposition allows the system to hop frequencies across time slots for interference reduction while maintaining low PAPR through contiguous tone assignments within each slot.
Data Source
AI summary
Facilitating frequency hopping for single carrier, frequency division multiple access (SC-FDMA) transmission is described herein. By way of example, user data transmitted within a transmission allocation unit can be frequency shifted with respect to time based slots of the allocation unit. As a result, frequency hopping can be accomplished while preserving single carrier constraints and a low peak to average power ratio (PAPR). Furthermore, various frequency shifted mechanisms are disclosed to accomplish preservation of single carrier restraints. For example, a scheduler can select between cyclic frequency shifting, transposed frequency shifting, and multiplexing of frequency selective scheduled and frequency hopped data based on an audit of scheduled data for the transmission allocation unit. As a result, the reduction in interference achieved through frequency hopping can be combined with the low PAPR for various data allocation configurations.