D2D Relay Tree for Mixed Point-to-Multipoint Wireless Networks
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Solution Overview
Problem
Existing point-to-multipoint wireless network technologies face inefficiencies due to the need to accommodate the worst channel conditions, leading to suboptimal resource allocation and throughput, especially in multimedia service distribution, where channel adaptation is limited by the absence of a return channel, resulting in degraded spectral efficiency and fairness in bit rate distribution among users.
Innovation Solution
A method that combines point-to-multipoint communications with device-to-device (D2D) relays to dynamically allocate resources and adapt modulation and coding schemes based on link quality, forming a tree structure of D2D links to relay content from better-quality users to others, thereby optimizing throughput and fairness across the network.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If point-to-multipoint radio communications are used to reach all users within the cell's radio coverage with the same transmission, then radio resources are used efficiently in theory, but the modulation and coding must be robust enough to ensure reception for each user, which limits throughput and spectral efficiency
Solution Approach 1:
The patent segments users into two groups: those with good channel conditions who receive content directly via point-to-multipoint transmission, and those with poor channel conditions who receive content via D2D relays. This segmentation allows the base station to use more efficient modulation and coding for the direct transmission while relays handle the difficult-to-reach users, resolving the contradiction between reliability for all users and spectral efficiency.
Solution Approach 2:
The patent introduces D2D relays as intermediary nodes between the base station and users with poor channel conditions. These relays receive content from the base station and forward it to target users, acting as mediators that enable reliable delivery without requiring the base station to use overly conservative modulation and coding, thus improving spectral efficiency.
2Reliability
If the modulation and coding are adapted to the worst channel conditions to ensure reception for all users, then reliability is maintained, but the overall performance of the communication cell is dictated by the adverse conditions
Solution Approach 1:
The patent segments users based on channel conditions into direct reception users (good channel) and relay users (poor channel). This allows different transmission strategies for different segments: efficient direct transmission for good channel users and relay-based transmission for poor channel users, preventing overall cell performance from being dictated by the worst conditions.
Solution Approach 2:
The patent applies local quality by tailoring transmission parameters and methods to specific user groups based on their individual channel conditions. Users with good channels receive optimized direct transmission, while users with poor channels receive relayed transmission, allowing each local group to receive appropriate service quality without compromising overall cell performance.
3Extent of automation
If resource allocation and transmission scheduling are controlled by the base station with periodic channel quality information, then control is centralized, but the complexity of finding optimal allocation grows exponentially with the number of users and links
Solution Approach 1:
The patent segments the resource allocation problem into two independent parts: base station-controlled allocation for direct transmissions and relay-controlled allocation for D2D transmissions. This segmentation reduces the complexity from exponential to polynomial by dividing the large optimization problem into smaller, manageable sub-problems that can be solved independently.
Solution Approach 2:
The patent introduces dynamic relay selection and allocation mechanisms that adapt to changing channel conditions in real-time. Relays dynamically adjust their transmission parameters and the base station dynamically selects optimal relays based on current channel quality, enabling centralized control to respond flexibly to conditions without requiring complex pre-computed allocation plans.
4Productivity
If D2D communications are used to reach only a subset of users with best channel quality while relaying to remaining users, then throughput is improved for direct receivers, but the system must manage multiple transmission paths and relay allocations
Solution Approach 1:
The patent segments transmission paths into direct point-to-multipoint links for users with good channels and D2D relay links for users with poor channels. This segmentation simplifies management by creating distinct, independent transmission domains with separate allocation mechanisms, reducing the complexity of managing multiple transmission paths.
Solution Approach 2:
The patent implements feedback mechanisms where users periodically report channel quality information to the base station, and relays provide feedback on their transmission status. This feedback enables dynamic adjustment of transmission strategies and relay allocations, simplifying system management by allowing adaptive response to changing conditions rather than requiring complex static plans.
Data Source
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AI summary
The invention relates to a method and a system for transmitting contents to a set of users UEk in a wireless communication network characterized in that it allocates the radio resources by executing at least the following steps: Measuring or evaluating the quality of the radio linkups between the base station BS and the users UEk (201 ), and the quality of the D2D radio linkups between the various users UEk (202), Selecting, as a function of the information in respect of quality of linkups, one, and only one, subset of users MG i *, of cardinality greater than or equal to 1, and a modulation and coding scheme MCS to be used for the point-to-multipoint transmission performed by the base station so as to guarantee the capacity to decode such a transmission to all the users forming part of the selected subset MGi*, Generating a tree A (206), of cardinality greater than or equal to 0, formed exclusively by linkups UEk→UEk (D2D) existing between the users so as to relay the content of the point-to-multipoint transmission from the users forming part of the subset MG i * as chosen in the previous step towards all the others, Allocating radio resources on the D2D links defined by the tree A.