Communicating Over Multiple Radio Access Technologies (Rats)

What is this patent about?

’544 is related to the field of wireless communication, specifically addressing the problem of delivering high-bandwidth multimedia content, such as mobile TV, to a large number of users over existing 3G networks. The background highlights the limitations of the UMTS air interface and network architecture in handling bandwidth-intensive multimedia broadcasts, leading to the development of MBMS (Multimedia Broadcast/Multicast Service) as an add-on framework. However, even with MBMS, the core network and radio access network elements face performance strain due to the high volume of broadcast traffic.

The underlying idea behind ’544 is to reduce network congestion by separating the control plane and user plane traffic for multimedia broadcasting across two different Radio Access Technologies (RATs). Instead of transmitting both the multimedia content and its associated control information over the same network, the invention proposes using one RAT for control signaling and another RAT for the actual multimedia data. This allows for a more efficient distribution of the network load and better utilization of available spectrum.

The claims of ’544 focus on a user equipment (UE) capable of transmitting a service request using a first RAT and, based on that request, receiving instructions to set up a bearer on a second, different RAT. The UE then receives multimedia data via the second RAT while simultaneously receiving other data via the first RAT. Crucially, the multimedia data received via both RATs uses the same packet data protocol and security keys , ensuring seamless integration and decryption.

In practice, the UE would initially communicate with the network using a common RAT like W-CDMA for control signaling, service registration, and security key exchange. Upon successful registration, the network would instruct the UE to tune into a different RAT, such as TD-CDMA, for receiving the actual multimedia broadcast. This 'one tunnel' approach bypasses the mobility anchor in the core network for the user plane traffic, reducing the processing load on that node.

This approach differentiates itself from prior solutions by strategically leveraging the characteristics of different RATs. For instance, the patent suggests using a paired spectrum (FDD) for control signaling and an unpaired spectrum (TDD) for the asymmetric multimedia traffic. By dedicating the unpaired spectrum entirely to downlink traffic, the invention maximizes spectrum utilization and reduces strain on the core network, ultimately improving the quality and scalability of multimedia broadcasting services.