Ranging Collision Elimination for Group Calls in Communication Networks
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Solution Overview
Problem
Group communication networks face ranging congestion and collisions due to limited random access codes, leading to uneven loading and increased call setup times, especially in public safety systems, where large groups can experience significant delays and reduced capacity.
Innovation Solution
Implementing a quasi-random access code generation method that uses a pre-established rule for each subscriber unit, based on a common seed such as a Group ID or cell ID, to generate unique ranging codes, avoiding collisions and reducing congestion by ensuring each member selects a distinct code.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If random access codes are used for subscriber units to join group calls, then individual identification is enabled, but ranging collisions and congestion occur due to limited code availability
Solution Approach 1:
The patent segments the random access code space into group-specific code sets. Each group is assigned a unique seed value that generates a dedicated subset of ranging codes through deterministic pseudo-random generation. This segmentation ensures that subscriber units in different groups use disjoint code sets, eliminating inter-group collisions while maintaining individual identification capability within each group.
Solution Approach 2:
The patent performs preliminary code assignment by pre-calculating and storing group-specific code sets before the actual ranging process. The network entity assigns a unique seed to each group in advance, and the corresponding pseudo-random code sequence is pre-generated and stored. When a group call occurs, subscriber units simply retrieve their pre-assigned codes without needing to generate them dynamically, reducing real-time collision probability.
2Manufacturing precision
If dedicated codes are assigned to each subscriber unit in a group, then ranging collisions are eliminated, but code loading becomes uneven and additional page message bits are required
Solution Approach 1:
The patent enables subscriber units to self-determine their ranging codes using a deterministic pseudo-random generator seeded with their unique identifier and the group seed. Each subscriber unit independently generates their code by applying the same algorithm with their specific input parameters, eliminating the need for the network to transmit dedicated code assignments in page messages. This self-service approach maintains code uniqueness while simplifying the page message structure.
3Manufacturing precision
If time separation is used to separate ranging responses, then code collisions are reduced, but call setup time increases proportionally to the number of group members
Solution Approach 1:
The patent transitions from time-domain separation to code-domain separation. Instead of sequentially timing ranging responses to avoid collisions, the system uses deterministic pseudo-random code generation to create orthogonal code sets for different groups. This dimensional shift from temporal to spectral/code space allows simultaneous ranging attempts without collisions, reducing call setup time while maintaining collision avoidance.
Data Source
AI summary
A network entity and method for eliminating ranging collisions for a group call in a communication network includes a step 300 of provisioning a pre-established rule for all members of a group, the rule including a common random number generator seed. A next step 302 includes initiating a group communication to subscriber units belonging to a group. A next step 304 includes generating a list of unique ranging codes for the members of the group using the common seed. A next step 306 includes each member of the group transmitting on its unique ranging code.