22-09-2008, 10:00 AM
Definition
The vision of the OpenRAN architecture is to design radio access network architecture with the following characteristics:
1.Open,
2.Flexible,
3.Distributed,
4.Scalable.
Such architecture would be open because it defines open, standardized interfaces at key points that in past architectures were closed and proprietary. It would be flexible because it admits of several implementations, depending on the wired network resources available in the deployment situation. It would be distributed because monolithic network elements in architectures would have been broken down into their respective functional entities, and the functional entities would have been grouped into network elements that can be realized as a distributed system.
The architecture would define an interface with the core network that allows the core network to be designed independently from the RAN, preserving access network independence in the core. Finally, the architecture would not require changes in radio page link protocols; in particular, a radio page link protocol based on IP would not be necessary. This document presents the first steps in developing the OpenRAN vision. In its first phase, the subject of this document, the OpenRAN architecture is purely concerned with distributing RAN functions to facilitate achieving open interfaces and flexible deployment. The transport substrate for implementing the architecture is assumed to be IP but no attempts is made to optimize the use of IP protocols, nor are specific interfaces designated as open.
The architecture could as well be implemented on top of existing functional architectures that maintain a strict isolation between the transport layer and radio network layer, by splitting an existing radio network layer into control and bearer parts. In addition, interoperation with existing core and RAN networks is supported via interworking functions. Chapters 7 through 11 in this report are exclusively concerned with this first phase of the
architecture, and it is possible that the architecture may change as the actual implementation of the OpenRAN is considered and For Further Study items are resolved.
In its second phase, consideration of protocols for the interfaces leads to considering how IP can be used more efficiently in the radio access network. In addition, the architecture currently has a CDMA focus, since CDMA radio access networks tend to be the most demanding in terms of functionality. In the second phase, how the architecture applies to radio -link protocols based on other principles will be considered. Finally, the second phase is expected to resolve all For Further Study items from phase 1 and to generate a requirements traceability analysis. This analysis is necessary to validate that the architecture does, in fact, meet the principles and requirements laid out .ts third phase, the addition of a radio access network protocol general enough to support multiple radio page link types and an operations and maintenance protocol based on standard IP operations and maintenance protocols may allow a forward looking, truly global RAN to emerge, customizable to a particular radio page link protocol and able to run multiple radio page link types simultaneously. It is expected that the first phase of this report could serve as input into the advanced architecture planning activities of 3GPP and 3GPP2.
