Network Node Random Access Success Verification
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Solution Overview
Problem
Current wireless communications networks face challenges in detecting and resolving preamble collisions during contention-free random access procedures, especially when non-reserved signals are used, leading to potential interference and errors due to the lack of methods to manage collisions in NB-IoT and LTE systems.
Innovation Solution
A method is introduced where a network node determines the success of a random access procedure by verifying whether the L2/L3 message originated from the intended wireless device after sending a PDCCH order indicating a non-reserved signal, allowing for the use of a faster contention-free random access procedure without reserved signals, and enabling detection and resolution of preamble collisions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of time
If contention-free random access procedure with non-reserved signals is used, then latency is reduced and processing speed is improved, but collision detection capability deteriorates due to lack of reserved preambles
Solution Approach 1:
The patent implements feedback mechanisms where the network node monitors uplink transmissions and sends acknowledgments or negative acknowledgments to the wireless device. When a collision is detected through feedback (e.g., failed decoding of L2/L3 message), the network can request retransmission, allowing the system to maintain reliability while using non-reserved signals for faster initial access.
Solution Approach 2:
The patent introduces intermediary verification steps between the random access preamble transmission and the final access confirmation. The network node uses intermediate messages (RAR, L2/L3 messages) to verify successful access and detect collisions, acting as mediators that bridge the gap between fast non-reserved signal access and reliable collision detection.
2Device complexity
If non-reserved signals are used for random access, then device complexity is reduced and ease of operation is improved, but measurement precision deteriorates due to inability to verify message origin
Solution Approach 1:
The patent uses message identifiers and scrambling codes as analogous to 'color changes' to distinguish messages from different wireless devices. Even when using non-reserved signals, each device's messages can be uniquely identified through device-specific scrambling sequences or message identifiers, enabling verification of message origin without increasing signal management complexity.
Solution Approach 2:
The patent employs copying techniques where the network node receives and verifies copies of messages containing device identifiers or scrambling sequences that originate from the wireless device. This allows verification of message authenticity without requiring complex signal management, as the verification is done through comparing received message copies against expected device-specific patterns.
3Reliability
If contention-based random access is used, then collision management is improved, but latency increases and processing speed decreases
Solution Approach 1:
The patent implements a dynamic approach that allows the system to switch between contention-free and contention-based procedures based on current network conditions and device states. The network node can dynamically determine whether to use non-reserved signals for fast access or fall back to reserved preambles for collision-prone scenarios, optimizing both speed and reliability adaptively rather than using a fixed procedure.
Solution Approach 2:
The patent changes parameters such as the set of available preambles, message formats, and verification methods based on whether contention-free or contention-based access is being used. By dynamically adjusting these parameters, the system can achieve fast access when conditions permit while maintaining collision management capabilities when needed, resolving the contradiction between speed and reliability.
Data Source
AI summary
Method performed by a network node in communication with a first wireless device. The network node and the first wireless device operate in a wireless communications network. The network node determines whether or not a random access procedure for the first wireless device was successful. The determining is performed after the following actions in the random access procedure: a) a first Physical Downlink Control Channel, PDCCH, order indicating a non-reserved signal has been sent to the first wireless device, the signal being one of: a preamble, a tone and a subcarrier, and b) an L2/L3 message has been received after the sending of the first PDCCH order. The determining is based on verifying whether or not the L2/L3 message originated in the first wireless device.