MBMS Control Plane Coordination in Flat RAN Base Stations
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Solution Overview
Problem
In flat Radio Access Network (RAN) architectures, there is a lack of practical solutions for coordinating Multimedia Broadcast Multicast Services (MBMS) control plane across base stations, which hinders efficient MBMS transmission and reception, especially in Wideband CDMA networks where centralized control is not available.
Innovation Solution
Base stations in a flat RAN share MBMS control plane information with neighboring stations by transmitting Radio Resource Control (RRC) messages via the standardized lur interface, using a new Radio Network Subsystem Application Part (RNSAP) class 2 procedure called MCCH Information Transfer, allowing each base station to provide MBMS user plane configuration for its own and neighboring cells.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If centralized control is used to coordinate MBMS across base stations, then MBMS control plane coordination is improved, but device complexity and network architecture complexity increase
Solution Approach 1:
Each base station autonomously acquires and broadcasts MBMS control plane information received from the core network, without requiring centralized coordination. The base station independently manages its own MBMS control plane functions by obtaining configuration data via the lur interface and making it available to user equipment, thereby eliminating the need for complex centralized control mechanisms.
2Reliability
If MBMS control plane information is shared between neighboring base stations, then UE reception performance is improved, but information transmission overhead increases
Solution Approach 1:
The MBMS control plane information broadcast by each base station serves dual purposes: it provides control plane data for the base station's own cells and simultaneously provides control plane data for neighboring cells. By making the MBMS control plane information universally available through local base station broadcasts, the system eliminates the need for separate information exchange mechanisms between base stations, thereby reducing transmission overhead while improving UE reception performance.
3Area of stationary object
If base stations transmit MBMS control plane information for neighboring cells, then service coverage is improved, but transmission power requirements increase
Solution Approach 1:
Each base station acts as an intermediary by acquiring MBMS control plane information from the core network via the lur interface and re-broadcasting it locally. This intermediary approach allows user equipment to receive control plane information for neighboring cells from their current base station without requiring those base stations to increase transmission power, as the information is already available in the local broadcast channel.
Data Source
AI summary
In a flat Radio Access Network (RAN) architecture, each base station (16) shares Multimedia Broadcast Multicast Services (MBMS) control plane information with its neighboring base stations (16), by sharing with neighboring base stations (16) the same control plane information that the base station (16) transmits via its air interface (24). For example, in a Wideband CDMA embodiment, where each base station (16) in a flat WCDMA RAN (12) is referred to as a NodeB÷, one NodeB÷ shares MBMS control plane information with one or more neighboring NodeB+s. Such sharing allows a given base station (16-1) not only to broadcast MBMS configuration information for its own cells (18-1), but also to broadcast such information for one or more neighboring cells (18-2, 18-3) that operate under control of one or more neighboring base stations (16-2, 16-3). Thus, a user equipment (UE) (22) camping in the given base station's cell (18-1) is provided with the information needed to acquire the MBMS user plane in its current cell (18-1) and in one or more of the neighboring cells (18-2, 18-3). In this manner, the UE (22)—also referred to as a mobile terminal—can receive MBMS transmissions from multiple base stations (16-1, 16-2, 16-3), for selective and/or soft combining. UE reception performance is thereby improved and base stations (16) in a flat RAN (12) generally can send MBMS transmissions at a lower power.