D2D Switching Between Cellular and License-Exempt Bands
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Solution Overview
Problem
The existing technologies face challenges in efficiently switching data communications between licensed and license-exempt frequency bands, leading to potential data loss and high latency due to contention protocols and inefficient use of shared spectrum, particularly in direct D2D communication scenarios.
Innovation Solution
A method involving a pre-switch notification to adopt a temporary strategy for data-related transmissions, such as no-new-data-transmission or no-feedback-transmission, before switching between licensed and license-exempt frequency bands, allowing for reduced latency and guaranteed data transfer without loss.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional contention protocols are used for switching between licensed and license-exempt bands, then fairness among users is maintained, but switching latency increases and data loss occurs
Solution Approach 1:
The system performs preliminary actions by sending a pre-switch notification before the actual frequency band switching occurs. This allows the receiving device to prepare for the switch in advance, adopting a temporary transmission strategy that prevents data loss during the transition, thereby reducing overall switching latency while maintaining reliability
Solution Approach 2:
The transmission strategy dynamically changes based on the switching state. During the pre-switch phase, a temporary strategy is adopted; after switching, the strategy is discontinued. This dynamic adaptation allows the system to optimize performance for each phase of the switching process, reducing latency while preventing data loss
2Productivity
If license-exempt band is used for D2D communication, then traffic offloading is achieved, but channel availability is limited by contention time limits
Solution Approach 1:
The system ensures continuous data transmission by coordinating switching between licensed and license-exempt bands. The pre-switch notification mechanism allows seamless transition between bands without interruption to the D2D communication flow, maintaining continuous useful action despite the limitations of license-exempt band occupation duration
3Adaptability or versatility
If frequent switching between bands is performed, then shared spectrum utilization is optimized, but switching overhead increases
Solution Approach 1:
The pre-switch notification acts as an intermediary mechanism that simplifies the switching control process. By notifying devices in advance before switching occurs, the system reduces the complexity of coordinating frequent band switches, allowing optimized spectrum utilization without proportionally increasing control overhead
Data Source
AI summary
A method and an apparatus for switching D2D data communications between a licensed and a license-exempt band are disclosed. A D2D device receives from a cellular network a pre-switch notification to prepare for a switch of its D2D communications, and in response adopts a temporary strategy for conducting its D2D transmissions prior to the switch. After the switch the D2D device discontinues the temporary strategy. In one embodiment the temporary strategy and its duration are indicated in the pre-switch notification. Two example temporary strategies are presented: ‘no-new-data’ where new data transmissions are suspended and data re-transmissions are sent with high reliability; and ‘no-feedback’ where new data is sent with high reliability and data re-transmissions are suspended. Different embodiments have the cellular network access node or D2D device contending for the radio resource in the license-exempt frequency band.