MBS Synchronization in Wireless Base Stations
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Solution Overview
Problem
Current wireless communication systems face challenges in maintaining synchronization of Multicast/Broadcast Service (MBS) downlink flows between Base Stations (BSs) over WiMAX radio links, particularly due to high transmission jitter and mutual interference in overlapping MBS zones, which affects bandwidth utilization and resource allocation.
Innovation Solution
A method and apparatus for synchronizing MBS data transmission across multiple BSs, involving the provision of synchronization information to ensure simultaneous starting times, recovery of faulty data, and allocation of time and frequency resources, while allowing overlapping zones to transmit different data over the same subcarriers, using graph coloring for resource management.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If multiple Base Stations transmit MBS data simultaneously over the same subchannels to improve signal energy and reception reliability, then the mobile terminal's ability to receive data correctly is improved, but transmission synchronization becomes difficult to maintain due to high jitter in packet networks and mutual interference occurs in overlapping MBS zones
Solution Approach 1:
The patent segments the MBS transmission problem by introducing MBS_ZONE identifiers to divide the network into distinct synchronization zones. Each zone is independently synchronized, allowing BSs within the same zone to transmit simultaneously while preventing interference with BSs in other zones. This segmentation resolves the contradiction by enabling reliable simultaneous transmission within zones while managing synchronization complexity through zone-based isolation.
Solution Approach 2:
The patent introduces synchronization reference signals and MBS_ZONE identifier messages as intermediary elements that mediate between the packet network's inherent asynchrony and the requirement for synchronized transmission. These intermediaries carry timing and zone information that enable BSs to align their transmissions despite jitter in the underlying network, thereby maintaining reliability without requiring complex direct synchronization between all BSs.
2Power
If MBS data is transmitted by multiple Base Stations simultaneously over the same subchannels to increase signal energy, then the combined signal energy received by mobile terminals is improved, but mutual interference occurs in overlapping MBS zones affecting resource allocation
Solution Approach 1:
The patent applies local quality by assigning different MBS_ZONE identifiers to different geographical or logical zones, allowing simultaneous transmissions with the same signal characteristics within each zone while preventing interference between zones. This enables the system to maintain high signal energy locally through coordinated transmission while eliminating mutual interference through zone-based differentiation.
Solution Approach 2:
The patent uses MBS_ZONE identifiers as a form of 'color coding' to distinguish between different transmission zones. Just as different colors can coexist without interfering with each other, different MBS_ZONE identifiers allow multiple simultaneous MBS transmissions to coexist without mutual interference, while still providing the signal energy benefits of multi-BS transmission within each zone.
3Reliability
If synchronization information is added to MBS packets to enable synchronization between Base Stations, then transmission synchronization can be maintained, but the packets cannot be used as a source for synchronization information since no synchronization-related information can be added
Solution Approach 1:
The patent extracts synchronization information from the MBS data packets by identifying and removing packets that contain synchronization reference signals or MBS_ZONE identifier information. This allows the system to use dedicated synchronization packets separately for timing alignment while keeping the main MBS data packets focused on content delivery, thereby maintaining synchronization accuracy without complicating the processing of regular data packets.
4Adaptability or versatility
If MBS connection is maintained regardless of MS operation mode to ensure continuous service, then service availability is improved, but bandwidth utilization decreases due to continuous transmission requirements
Solution Approach 1:
The patent implements periodic action by allowing MBS transmissions to be scheduled in periodic intervals rather than continuous streams. The MBS connection remains established and available regardless of MS operation mode, but actual data transmissions occur periodically when needed, improving bandwidth utilization while maintaining service availability. The synchronization mechanism ensures that these periodic transmissions remain coordinated across multiple BSs.
Data Source
AI summary
A method and device are provided for synchronizing data transmission of multicasting/broadcasting services (MBS) by a plurality of Base Stations. Meanwhile, each of the Base Stations receives the MBS data to be transmitted and determines whether any of the MBS data has not been properly received. If so, the respective Base Station may initiate a process to recover the missing MBS data and/or to obtain information regarding the missing data to determine the duration of the time period that would have been required for transmitting the missing MBS. If the missing data has not been timely recovered, the respective Base Station determines a starting point and the duration of a silence period based on the information obtained, and refrains from transmitting signals along a communication channel allocated for transmission of MBS data, during that silence period.