IoT Random Access Code-Domain Multiplexing for Fewer Collisions
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Solution Overview
Problem
Existing wireless communication systems face inefficiencies in resource usage and high collision probabilities due to the slotted Aloha scheme, particularly for low-complexity IoT devices with limited power and no independent signal generation, leading to delayed access and increased maintenance costs.
Innovation Solution
Implement code-domain multiplexing by configuring IoT devices with circular-shifted binary modulated sequences for random access transmissions, allowing for efficient multiplexing and reducing collision probabilities without requiring device-side awareness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If slotted Aloha scheme is used for random access, then device complexity is reduced, but collision probability increases and resource utilization deteriorates
Solution Approach 1:
The patent introduces code domain multiplexing as an additional dimension for resource separation. Instead of only using time slots (1D), the system now uses both time slots and orthogonal codes (2D), allowing multiple devices to transmit simultaneously in the same time slot with different codes, thereby reducing collisions while maintaining low device complexity
Solution Approach 2:
The patent segments the random access resources by dividing them into multiple orthogonal code sequences. Each device is assigned a specific orthogonal code, creating segmented transmission paths that prevent collisions even when devices transmit in the same time slot, thus improving reliability without increasing device complexity
2Ease of operation
If slotted Aloha scheme is used for random access, then ease of operation is improved, but resource utilization deteriorates
Solution Approach 1:
By adding the code domain dimension to the existing time domain structure, the system achieves better resource utilization. Multiple devices can share the same time slot using different orthogonal codes, effectively multiplying the available resources without complicating the device operation
Solution Approach 2:
The orthogonal code sequences provide universal multiplexing capability across all random access transmissions. The same set of orthogonal codes can be reused in different time slots and across different devices, creating a flexible and efficient resource allocation system that improves productivity while maintaining ease of operation
3Productivity
If more devices transmit in the same time slot, then productivity is improved, but collision probability increases
Solution Approach 1:
The patent resolves this contradiction by transitioning from one-dimensional time slot allocation to two-dimensional time-code resource allocation. Devices can transmit in the same time slot as long as they use different orthogonal codes, allowing increased productivity without proportionally increasing collision probability
Solution Approach 2:
The system uses orthogonal code sequences that are copies of the base sequence with different cyclic shifts. These copied sequences maintain orthogonality properties, allowing multiple devices to transmit simultaneously with identical power levels and time slots while preventing collisions through code differentiation
Data Source
AI summary
Various aspects of the present disclosure relate to transmitting a first random access configuration comprising code domain information and receiving a first set of random access transmissions from a set of internet-of-things (IoT) devices, each random access transmission of the first set of random access transmissions multiplexed according to the code domain information. Aspects of the present disclosure may relate to transmitting a second random access configuration to a subset of IoT devices of the set of IoT devices based at least in part on a collision between a subset of random access transmissions of the first set of random access transmissions, where the subset of random access transmissions is associated with the subset of IoT devices, and receiving a second set of random access transmissions based on the second random access configuration.