The Open Base Station Architecture Initiative, OBSAI, which pushes open interface specs for base stations and module specs for transport, control, baseband and radio, has made its RF interface spec freely available for download from its website.
Until now, a company wanting to obtain the spec had to be a member of OBSAI, which is an alliance of base station and component vendors led by Nokia and Samsung, with other base station vendors ZTE, Alcatel and Panasonic as members. While joining up is a simple process, OBSAI officials said it has become clear that certain companies were reluctant to do so on account of sector politics, and did not want to be seen to be too closely aligned with Nokia or Samsung.
By making the RF spec freely available, companies can use it as the basis for their products, making only minor changes to maintain an image of independence while at the same time reaping the benefits of the existence of OBSAI, which gives them the ability to source components from a wider range of suppliers than if they were entirely proprietary.
The backdrop to this latest move by OBSAI is its rivalry with another industry grouping, which is commonly referred to by the name of its spec: the Common Public Radio Interface, CPRI. The CPRI parties are Ericsson, Huawei, NEC, Nortel, and Siemens. The group proposes a common spec for only one area of base station technology, namely the high-data-rate interface between the baseband and RF circuitry: the RF module interface, and then only for W-CDMA, whereas OBSAI also seeks to address cdma2000 and WiMAX.
The CPRI spec corresponds to OBSAI’s Reference Point 3, RP3, spec for the interface between the RF and baseband modules, which is what the Nokia- and Samsung-led group is now making freely available for download. OBSAI’s other two specs are RP1 for the control module interface (between the control module and the transport, baseband and RF modules) and RP2 for the transport module interface (between the transport and baseband modules).
Apart from being specific to a single interface, the CPRI spec is also based on a specific assumption, said Peter Kenington, director of the advanced technology base station group at RF system developer Andrew Corp and the technical chair on OBSAI’s management board. They think base stations will all use remote radio heads with no more cabinet-based ones, whereas we have a standard version of RP3 for cabinet-based and another for remote, he said. The CPRI spec has been freely available for download since 2004.