D2D Transmission Power Control for Cellular Interference
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Solution Overview
Problem
Current mobile communication systems face challenges in enabling device-to-device (D2D) communication on the same resources as cellular communication without interfering with cellular throughput, as existing technologies do not specify how to utilize occupied cellular resources for D2D communication without causing interference.
Innovation Solution
A method is developed to determine the maximum transmission power for D2D communications using path loss measurements and correction values, allowing D2D devices to operate on shared resources without impacting cellular networks, and employing blind interference cancellation to eliminate interference from cellular uplink transmissions, thereby enabling simultaneous D2D and cellular communication without additional signaling.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If D2D communication uses the same resources as cellular communication, then resource utilization efficiency is improved, but interference between D2D and cellular signals occurs
Solution Approach 1:
The patent applies parameter changes by modifying the power domain parameter to enable multiple users to share the same time-frequency resources. Different users transmit at different power levels, allowing the system to maintain resource utilization efficiency while managing interference through power differentiation. The receiver uses successive interference cancellation to decode signals by processing them in order of decreasing power level.
Solution Approach 2:
The patent converts the harmful interference effect into a beneficial feature by exploiting the power difference between signals. The stronger signal, instead of being purely interfering, becomes the first to be decoded and then subtracted from the received signal, enabling the recovery of weaker signals. This transforms the interference problem into a structured decoding process that improves overall system capacity.
2Productivity
If multiple users share the same resources simultaneously, then system throughput is improved, but signal decoding complexity increases
Solution Approach 1:
The patent applies preliminary action by performing signal decoding in a predetermined order based on power levels before complete signal separation is achieved. The receiver first decodes the strongest signal, subtracts it from the composite signal, then proceeds to decode the next strongest signal. This step-by-step preliminary decoding reduces the overall complexity compared to attempting to decode all signals simultaneously.
Solution Approach 2:
The patent segments the decoding process into multiple sequential stages, each handling one user's signal. Instead of attempting to decode all user signals in a single complex operation, the system divides the task into separate decoding steps, where each step processes one user's signal independently after removing previously decoded signals. This segmentation makes the overall decoding process more manageable and implementable.
Data Source
AI summary
The present invention provides a method of determining a transmission power for device to device, D2D, transmissions between a first user equipment device and a second user equipment device using transmission resources being used for transmissions to a cellular network entity by a third user equipment device, the method comprising determining a measure of a path loss between the cellular network entity and the first user equipment device, and using the measure of the path loss to determine a maximum transmission power such that the D2D transmissions are received at the cellular network entity with a signal level around or below a noise level.