ACK NACK Resource Differentiation in D2D Groupcast
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Solution Overview
Problem
In Device-to-Device (D2D) communication, the existing methods for transmitting reception confirmation responses in groupcast scenarios are inefficient, leading to a high burden on system resources due to the exponential increase in ACK/NACK feedback channels, which can overwhelm the system.
Innovation Solution
The proposed method differentiates resource regions for ACK and NACK responses, allowing for common use of these regions among D2D devices, with re-transmissions triggered only when energy above a predetermined value is detected in the NACK region, and adjusts transmission power based on pathloss to optimize signal reception.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If separate resource regions are allocated for each device's ACK/NACK feedback in D2D groupcast, then each device can transmit its reception confirmation response, but the number of required channels increases exponentially with group size, overwhelming system resources
Solution Approach 1:
Multiple devices in the D2D group share common resource regions for transmitting ACK/NACK feedback instead of each device having dedicated resources. This merging of resources dramatically reduces the total number of channels required from exponential to a manageable number, while maintaining the ability for all devices to provide reception confirmation responses.
Solution Approach 2:
The patent introduces spatial dimension (different resource regions) and temporal dimension (different transmission timing) to differentiate between multiple devices' feedback. By utilizing these additional dimensions, the system can support multiple devices sharing common resources without confusion, resolving the contradiction between reliability of feedback transmission and quantity of resources required.
2Quantity of substance
If a common resource region is shared by all devices for ACK/NACK transmission, then the number of channels is reduced, but devices with different pathloss experience unequal reception quality at the transmitting device
Solution Approach 1:
The patent applies different transmission power levels to different devices based on their individual pathloss characteristics. Devices experiencing higher pathloss transmit with higher power, while devices with lower pathloss transmit with lower power. This local quality adjustment ensures that all devices' feedback signals arrive at the transmitting device with comparable reception quality, resolving the contradiction between resource efficiency and signal quality.
Solution Approach 2:
The transmitting device adjusts the transmission power parameter of each receiving device based on measured pathloss values. By dynamically changing this parameter, the system compensates for varying channel conditions and ensures uniform signal quality at the receiver, maintaining measurement precision while using shared resources.
3Reliability
If transmission power is increased for devices with high pathloss to ensure reception quality, then signal reliability improves, but overall system energy consumption increases
Solution Approach 1:
Instead of all devices transmitting at maximum power, the patent applies partial action by having each device transmit only at the necessary power level required to overcome its specific pathloss. Devices with low pathloss transmit at lower power, avoiding excessive energy consumption, while still ensuring adequate reception quality. This resolves the contradiction between reliability and energy consumption by applying the right amount of action only where needed.
Data Source
AI summary
One embodiment of the present invention relates to a method for transmitting and receiving signals between devices in a wireless communication system, the signal transmission and reception method comprising the steps of: receiving, by a first device, a signal from a second device; and transmitting, by the first device, a reception confirmation response to the signal, wherein a resource region in which the reception confirmation response is transmitted is differentiated according to whether the reception confirmation response is ACKnowledgement (ACK) or Negative ACKnowledgement (NACK), and the resource region in which the reception confirmation response is transmitted is commonly used for devices which have received the signal.