D2D Discovery Signal Collision Avoidance via Dynamic Resource Allocation
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Solution Overview
Problem
In cellular communication systems, device-to-device (D2D) communication faces challenges in resource allocation and interference, particularly in inter-PLMN and intra-PLMN scenarios, where D2D devices may collide due to unsynchronized resource allocation, leading to reduced detection of discovery signals and increased interference.
Innovation Solution
A method for D2D enabled devices to assign time and subcarriers based on dynamic rules, incorporating identifiers like carrier frequency, network identity, and cell identity, to reduce collision risks through jittering and randomization of timing and subcarrier selection, allowing for coordinated resource reuse.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If D2D devices use fixed resource allocation patterns, then resource utilization is simplified, but collision probability increases and detection reliability decreases
Solution Approach 1:
The patent applies dynamics by transitioning from fixed resource allocation patterns to dynamic selection mechanisms. Each D2D device dynamically selects time resources and subcarriers based on randomization functions and jittering techniques, allowing the allocation pattern to change over time and adapt to varying network conditions, thereby reducing collision probability while maintaining manageable complexity through standardized dynamic rules.
Solution Approach 2:
The patent changes key parameters including time offset values and subcarrier indices through randomization functions that incorporate device identifiers such as PLMN ID, cell ID, and device ID. These parameter changes create diverse transmission patterns across devices, reducing the likelihood of simultaneous transmissions on the same resources while maintaining systematic allocation through the randomization function.
2Productivity
If D2D devices transmit discovery signals simultaneously on the same resources, then resource utilization efficiency increases, but interference between devices increases
Solution Approach 1:
The patent segments the time-frequency resource space into multiple dimensions: multiple time offsets within a periodic schedule and multiple subcarrier sets. Each D2D device is assigned a specific combination of time offset and subcarrier based on its identifier, effectively segmenting the shared resource pool into device-specific transmission slots that reduce mutual interference while maintaining overall resource utilization efficiency.
Solution Approach 2:
The patent introduces a randomization function as an intermediary mechanism that mediates between the desire for high resource utilization and the need to minimize interference. This intermediary algorithm processes device identifiers and generates diversified time-frequency allocations, acting as a coordinator that enables simultaneous transmissions on different resources while preventing collisions through systematic randomization.
3Reliability
If D2D devices use random timing assignment, then collision probability decreases, but timing synchronization difficulty increases
Solution Approach 1:
The patent implements periodic action by establishing a periodic time schedule with predetermined time offsets for D2D discovery signal transmissions. Devices transmit at regular intervals according to this periodic pattern, which simplifies synchronization requirements compared to completely random timing. The periodic structure provides predictable transmission cycles that ease timing coordination while the randomization within each period maintains collision avoidance benefits.
Data Source
AI summary
A method performed in a device-to-device (D2D) enabled device, for transmitting discovery signals for enabling D2D communication establishment in a cellular communication system is disclosed. The method comprises assigning, by a controller of the device, a time in a periodic time schedule and at least a subcarrier among a plurality of subcarriers assigned for carrier for D2D communication of the communication system based on a dynamic rule for spreading timing and/or subcarrier selection for the discovery signal. Furthermore, the method comprises transmitting, by a transceiver of the device, the discovery signal according to the time and subcarrier assignment provided by the controller.