Resource Block Allocation in OFDMA Systems
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Solution Overview
Problem
In wireless networks, particularly those adhering to IEEE 802.11 standards, the allocation of Resource Blocks (RB) in OFDMA systems results in inefficiencies due to varying bandwidths and configurations, leading to leftover tones that go unused, thereby wasting usable bandwidth and reducing throughput.
Innovation Solution
Implementing a rate matching scheme that treats overhead tones such as DC, guard, and pilot tones as encapsulated units, not considering them during initial RB allocation, and instead allocates data tones first, followed by inserting overhead tones into punctured locations, ensuring all usable tones are utilized without waste.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If traditional RB allocation methods are used to accommodate varying bandwidths and configurations, then different users can be served with appropriate bandwidth, but leftover tones are created that waste usable bandwidth
Solution Approach 1:
The patent segments the frequency spectrum into resource blocks of a fixed size (e.g., 180 tones) rather than allocating variable-sized blocks to match each user's bandwidth requirements. This segmentation approach allows the system to serve multiple users with different bandwidth needs using a standardized RB structure, eliminating the need for variable RB sizes that create leftover tones.
Solution Approach 2:
The patent applies partial action by allocating resource blocks that may be larger than individually needed by single users, allowing multiple users to share larger RBs. This is similar to the concept of rate matching in LTE, where RBs are allocated in fixed units and then adapted through puncturing or rate matching to fit varying data rates and bandwidth requirements, thereby eliminating bandwidth waste.
2Ease of manufacture
If fixed RB size is used for all users, then allocation simplicity is maintained, but users with smaller bandwidth requirements experience reduced efficiency
Solution Approach 1:
The patent introduces dynamic adaptation to fixed RB allocations through rate matching techniques. While the physical RB structure remains fixed for simplicity, the system dynamically adjusts the effective bandwidth and modulation coding scheme (MCS) based on each user's actual requirements. This allows flexible adaptation of data rates and bandwidth usage without changing the underlying RB allocation mechanism.
Solution Approach 2:
The patent changes operational parameters such as modulation order and coding rate to adapt the effective data rate within fixed RB allocations. By adjusting these parameters dynamically based on user capabilities and channel conditions, the system optimizes throughput efficiency while maintaining the simplicity of fixed RB sizing for allocation purposes.
3Loss of energy
If variable RB sizes are implemented to match user bandwidths, then bandwidth utilization efficiency improves, but system complexity increases
Solution Approach 1:
The patent maintains segmentation into fixed-size resource blocks as the fundamental allocation unit, avoiding the complexity of variable RB size management. The fixed segmentation approach simplifies allocation algorithms and reduces processing overhead while still achieving efficient bandwidth utilization through higher-order modulation and rate matching techniques.
Data Source
AI summary
Techniques for resource block allocation in a multi-user MIMO High Efficiency WLAN system are provided. Specifically, teachings that when taken alone or together, provide a device or a group of devices with an improved resource allocation for the reduction of usable tone waste, are presented. The present disclosure includes a system that provides a user with a technique allocating data tones prior to the encapsulation unit or overhead tones on a resource block unit. Further, the total allocated bandwidth can be reduced prior resource allocation to overcome modulation and coding scheme downgrading caused by severe puncturing. Alternatively, only band edge basic resource blocks are reduced to account for overhead tones which largely reside on band edges.