End-to-End MAC Resource Allocation for Multi-Hop Wireless Networks
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Solution Overview
Problem
In multi-hop wireless networks, existing Medium Access Control (MAC) protocols face challenges in reducing end-to-end transmission delay, particularly in scenarios where each relay node issues resource requests only for the next link towards the destination, leading to increased queuing delays and uneven fairness between uplink and downlink communications.
Innovation Solution
A novel MAC method computes resource requests on an end-to-end basis instead of per link, allowing each node to request resources for all links between itself and the Base Station (uplink) or destination (downlink), enabling cumulative resource allocation and grant distribution, which aligns with frame-based Physical (PHY) layer scheduling in tree-topology networks with centralized control.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If each relay node issues resource requests only for the next link towards the destination, then the MAC protocol implementation is simplified, but the end-to-end transmission delay increases due to cumulative queuing delays at each hop
Solution Approach 1:
Instead of having each relay node independently request resources for its own link (bottom-up approach), the invention inverts the approach by having the Base Station compute cumulative resource requests from the root (BS) down to all relay nodes in the tree topology. This top-down inversion allows the BS to allocate resources for the entire end-to-end path in a single scheduling decision, eliminating the cumulative queuing delay problem while maintaining implementation simplicity at the relay nodes.
2Productivity
If resource allocation is performed per link at each relay node, then local resource management is efficient, but fairness between uplink and downlink communications deteriorates
Solution Approach 1:
The invention merges the separate resource allocation decisions for uplink and downlink communications into a unified end-to-end resource allocation process at the Base Station. By computing cumulative resource requests that encompass both uplink (RN to BS) and downlink (BS to RN) traffic, and allocating resources in a single coordinated scheduling step, the system ensures fair treatment of both communication directions while maintaining overall system efficiency.
Data Source
AI summary
Requests of resources of uplink flows towards a base station (BS) and/or downlink flows towards end nodes are computed by each requesting node on an end-to-end basis. Each requesting node issues a cumulative request given by summing up the same request for each link separating the node from the BS plus each link separating the BS from the destination node, enabling the centralized node to perform connection based scheduling. The BS in response to all cumulative requests grants uplink and/or downlink resources for each link. The profile of grants is equal to the profile of requests when the amount of resources requested is below the maximum net throughput on MAC layer. When not below the maximum net through-put on MAC layer, the ideal profile of grants is normalized with respect to a ratio between the maximum net throughput on MAC layer and the amount of the overall requested resources.