Discovery Preamble Cyclic Prefix Design for Beamformed Wireless Interference
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Solution Overview
Problem
Wireless communication systems face interference and data loss due to time offsets in beamformed transmissions, particularly during discovery preamble exchanges, making it challenging to identify appropriate cyclic prefix durations for discovery preambles.
Innovation Solution
Applying a longer extended cyclic prefix to discovery preambles and generating cyclically periodic signals with multiple copies of the preamble, allowing receiving devices to identify the preamble regardless of delays, and using subcarrier spacing to determine CP lengths based on frequency bands.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a standard cyclic prefix is used for discovery preambles, then the system maintains simplicity and standard compliance, but interference and data loss occur due to time offsets in beamformed transmissions
Solution Approach 1:
The patent applies parameter changes by introducing multiple cyclic prefix length options (first cyclic prefix length and second cyclic prefix length) that can be selectively applied to discovery preambles based on transmission conditions. This allows the system to adapt the CP length parameter to compensate for time offsets in beamformed transmissions, thereby improving reliability without requiring complete system redesign
Solution Approach 2:
The patent implements dynamics by enabling dynamic selection between different cyclic prefix lengths based on detected time offsets and transmission scenarios. The system can switch between a first cyclic prefix length for certain conditions and a second cyclic prefix length for others, making the CP configuration adaptive rather than fixed, thus resolving the contradiction between reliability and complexity
2Reliability
If the cyclic prefix length is increased to protect against time offsets, then interference and data loss are reduced, but the transmission time and overhead increase
Solution Approach 1:
The patent applies partial action by using a first cyclic prefix length that provides sufficient protection against time offsets without excessive extension. The system selects the minimum necessary CP length (first cyclic prefix length) that ensures reliable preamble detection, avoiding the need for excessively long cyclic prefixes that would waste time while still achieving the reliability goal
3Reliability
If multiple copies of the discovery preamble are transmitted, then the receiving device can identify the preamble regardless of delays, but the transmission time and interference potential increase
Solution Approach 1:
The patent applies periodic action by transmitting multiple copies of the discovery preamble at different time positions within the discovery signal. This periodic repetition pattern allows the receiving device to detect the preamble regardless of time offsets or delays, as at least one copy will align with the receiver's timing. The periodic structure achieves high reliability without requiring excessive repetitions that would waste time
Data Source
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AI summary
Methods, systems, and devices for wireless communications are described. In some wireless communications systems, a wireless device may broadcast a discovery preamble to identify a receiving device or to identify a suitable beam for communicating with a receiving device prior to broadcasting a discovery message to the receiving device. In such systems, the wireless device may use the techniques described herein to generate the discovery preamble and to reduce interference between discovery preamble transmissions and avoid data loss. In one example, a wireless device may append a cyclic prefix (CP) to a discovery preamble with a suitable length to protect the discovery preamble from interference from another transmission. In another example, the wireless device may generate a cyclically periodic signal including multiple copies of the discovery preamble so a receiving device may be able to receive a portion of the signal and identify the discovery preamble.