Wireless Multicast Proxy for Reliable Media Delivery
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Solution Overview
Problem
Wireless local-area networks (WLANs) are unsuitable for distributing multicast packets of media due to high error rates, which significantly reduce the quality of media delivery services like IPTV, as multicast packets are not acknowledged in WLANs.
Innovation Solution
A wireless multicast proxy that identifies wireless clients based on IP multicast destination addresses and unicast MAC addresses, generating unicast packets for transmission, using a multicast snoop circuit to create a table from IGMP messages, and being compliant with IEEE standard 802.11 amendments, ensuring reliable data transmission.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If multicast packets are transmitted in WLANs, then media distribution capability is enabled, but error rate increases significantly
Solution Approach 1:
The patent introduces an access point as an intermediary device that receives multicast packets from the wired network and converts them into unicast packets for wireless transmission. This mediator translates between multicast and unicast protocols, enabling reliable wireless delivery while maintaining media distribution capability. The access point acts as a bridge between the multicast-oriented wired network and the unicast-reliable wireless network.
Solution Approach 2:
The invention changes the fundamental transmission parameter from multicast to unicast at the wireless interface. By converting the packet type and transmission mode, the system maintains compatibility with multicast sources while achieving the reliability of unicast transmission in the wireless medium. This parameter transformation resolves the contradiction between enabling multicast distribution and maintaining low error rates.
2Reliability
If unicast packets are used for wireless transmission, then transmission reliability improves, but network complexity increases
Solution Approach 1:
The access point serves as a centralized intermediary that handles all the complexity of unicast conversion. Instead of requiring each wireless client to implement complex multicast-to-unicast conversion logic, the access point centralizes this function, simplifying client devices while maintaining transmission reliability through unicast packets.
Solution Approach 2:
The access point performs multiple functions: it acts as a wireless router, a protocol converter, and a multicast listener. By consolidating these functions in a single device, the system achieves reliable unicast transmission without distributing complexity across multiple devices. The access point's multi-functionality absorbs the network complexity centrally.
Data Source
AI summary
An access point including a snoop circuit to generate a table including a plurality of entries, each entry associating a MAC address of a wireless client with a multicast IP address; to enable multicast traffic for a first wireless client in response to receiving a first message from the first wireless client by i) adding an entry to the table for the first wireless client in response to the entry not existing in the table, and ii) starting a timeout timer for the first wireless client, or by restarting the timeout timer in response to the entry for the first wireless client existing in the table; and to keep the multicast traffic for the first wireless client enabled as long as the timeout timer is reset before expiring. An output circuit transmits a packet to the first wireless client if the multicast traffic for the first wireless client is enabled.