Unified Sequence Number for Wireless Packet Ciphering
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Solution Overview
Problem
Wireless communication systems face delays in packet re-ordering and synchronization due to the remote location of Radio Link Control (RLC) entities, which can lead to issues during handovers between base stations.
Innovation Solution
Implementing a single full sequence number for both ciphering and re-ordering, allowing processors to generate and use partial sequence numbers for re-ordering and deciphering, thereby reducing overhead and ensuring synchronized sequence numbers across base stations during handovers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of time
If RLC is moved to the base station to reduce feedback delay, then processing delay is reduced, but sequence number synchronization becomes complex during handover
Solution Approach 1:
The sequence number is segmented into two parts: a base sequence number (BSN) that remains constant during handover, and a packet sequence number (PSN) that increments with each packet. This segmentation allows the BSN to provide synchronization stability while the PSN handles packet-level sequencing, resolving the contradiction between reduced delay and synchronization complexity.
Solution Approach 2:
The base sequence number acts as an intermediary that carries handover information and provides a stable reference during base station transitions. This intermediary element enables seamless handover without requiring complex synchronization protocols, as the BSN is inherited or transferred between base stations while the PSN continues to increment locally.
2Adaptability or versatility
If separate sequence numbers are used for ciphering and re-ordering, then functional independence is achieved, but overhead increases
Solution Approach 1:
The patent merges the ciphering sequence number and re-ordering sequence number into a single unified sequence number structure. This unified sequence number serves both ciphering operations and packet re-ordering functions simultaneously, eliminating the overhead of maintaining separate sequence numbers while preserving the functional independence needed for both operations through the BSN-PSN segmentation.
Data Source
AI summary
Techniques for performing ciphering and re-ordering using a single full sequence number are described. A transmitter ciphers input packets to obtain ciphered packets, with each input packet being ciphered with a full sequence number. The transmitter generates output packets for the ciphered packets, with each output packet including a partial sequence number used for re-ordering and derived from the full sequence number. The full sequence number may be incremented for each input packet or each byte of each packet. The partial sequence number may be used as a sequence number for RLC and may be used for re-ordering, duplicate detection, error correction, and/or other functions. A receiver performs the complementary processing, re-orders received packets based on the partial sequence number included in each packet, and deciphers the received packets using the partial sequence number included in each received packet.