Handover SFN Indication in Wireless Random Access
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Solution Overview
Problem
Conventional wireless communication systems experience delays and service interruptions during handovers due to the time-consuming process of obtaining the system frame number (SFN) from a target cell, especially when using broadcast channels, which is essential for optimal communication and resource allocation.
Innovation Solution
Incorporating a method to provide the system frame number (SFN) directly to terminals during a random access procedure in wireless communication systems, by including it in Random Access Responses (RARs) or MAC sub-headers, allowing terminals to obtain SFN information promptly during the handover process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of information
If the terminal obtains the SFN from a broadcast channel provided by the target cell, then the terminal can acquire the SFN information, but this causes an appreciable amount of delay and service interruption
Solution Approach 1:
The SFN information is prepared and made available in the Random Access Response (RAR) message before the terminal needs to use it for uplink transmission. The base station includes the current SFN in the RAR message that is sent during the random access procedure, so the terminal receives the SFN information as part of the normal handover process without needing to separately monitor broadcast channels.
2Loss of information
If the terminal obtains the SFN from a broadcast channel, then the terminal can get the SFN, but the process is time-consuming and results in service interruption
Solution Approach 1:
The SFN information delivery is merged with the existing Random Access Response (RAR) message transmission. Instead of being a separate operation, the SFN is included as part of the RAR message that the base station already sends to the terminal during the random access procedure. This combining of information delivery with an existing communication step eliminates the need for additional time-consuming operations.
3Reliability
If the terminal requires knowledge of target cell parameters for uplink frequency hopping and resource scheduling, then proper communication can be established, but obtaining these parameters from broadcast channels causes delay
Solution Approach 1:
The base station prepares and includes the SFN parameter in the Random Access Response (RAR) message before the terminal needs to use it for uplink frequency hopping and resource scheduling. This preliminary provision of the parameter ensures that the terminal has all necessary information immediately available when needed for reliable communication, without the delay of separate parameter acquisition.
Data Source
AI summary
Systems and methodologies are described that facilitate system frame number (SFN) indication and identification during a random access procedure (e.g., associated with a handover). As described herein, a target cell can configure one or more Random Access Responses (RARs) designated for transmission to a terminal during the access phase of a handover to include the SFN of the target cell. Techniques are further described herein by which the target cell can include SFN information in a sub-header associated with a RAR, in the payload of a RAR, and/or in other appropriate manners. In addition, the target cell can configure one or more flags of the RAR to indicate the presence of SFN information. Upon receiving a RAR with embedded SFN information, a terminal can utilize the SFN for operations such as frequency hopping or uplink resource configuration as described herein.