OFDMA Frame Boundary Adjustment for Asynchronous Interference
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Multi-tier OFDMA overlay networks face significant challenges in managing asynchronous interference, which is more difficult to mitigate than synchronous interference due to frames arriving outside or within the cyclic prefix, leading to increased noise floors and degraded signal-to-noise and interference ratios.
Innovation Solution
The lower-tier base station adjusts its OFDMA frame boundaries to align uplink and downlink transmissions with those of the higher-tier, ensuring frames arrive within the cyclic prefix, thereby reducing asynchronous interference and allowing for synchronous interference mitigation techniques to be applied.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If same-frequency multi-tier overlay networks are deployed to increase network capacity and coverage, then network productivity and service area are improved, but asynchronous interference increases making interference management significantly more difficult
Solution Approach 1:
The patent changes the timing parameter of frame transmission by introducing a frame boundary adjustment mechanism. The lower-tier base station shifts its frame boundaries relative to the higher-tier base station to control the arrival time of frames, ensuring they fall within the cyclic prefix period. This parameter change transforms the interference from asynchronous (outside cyclic prefix) to synchronous (within cyclic prefix), resolving the technical contradiction.
2Device complexity
If frame boundaries are not adjusted, then device complexity is reduced, but asynchronous interference management becomes significantly more difficult
Solution Approach 1:
The patent applies preliminary action by pre-adjusting the frame boundaries at the lower-tier base station before transmission occurs. The frame boundary adjustment is calculated and applied in advance based on the relationship between tiers, so that when frames are transmitted, they automatically arrive within the cyclic prefix of the receiving tier. This preliminary timing alignment prevents asynchronous interference from occurring in the first place.
3Adaptability or versatility
If frames arrive outside the cyclic prefix, then transmission timing flexibility is improved, but asynchronous interference is generated that is significantly more difficult to manage
Solution Approach 1:
The patent introduces dynamic frame boundary adjustment where the lower-tier base station adaptively shifts its frame boundaries based on the higher-tier timing. This dynamic adjustment mechanism allows the system to maintain timing flexibility while ensuring that frames always arrive within the cyclic prefix, converting what would be asynchronous interference into manageable synchronous interference that can be handled by existing OFDMA cyclic prefix protection mechanisms.
Data Source
AI summary
Embodiments of a base station and method for reducing asynchronous interference in a multi-tier OFDMA overlay network are generally described herein. In some embodiments, a lower-tier base station is configured to adjust OFDMA frame boundaries to cause frames communicated by a higher-tier to arrive within a cyclic prefix at the lower-tier base station. The lower-tier base station may also be configured to adjust OFDMA frame boundaries to cause frames communicated by a lower-tier of the network to arrive within a cyclic prefix at a higher-tier mobile station. Accordingly, frames from one tier may arrive within the cyclic prefix of another thereby reducing asynchronous interference.