Who is OBSAI

OBSAI is a group of nearly 70 leading manufacturers of wireless infrastructure equipment, related modules and components from all over the world. After the foundation in October 2002, the members have worked together now for a year to agree open specifications for certain parts of the base stations' internal architecture and key interfaces. As of the end of October 2003, a complete set of OBSAI specifications is now available.

NEC Electronics as a major supplier of semiconductor products to the mobile infrastructure market is member in OBSAI. For further information about OBSAI, please have a look to the OBSAI web-site: http://www.obsai.com/

OBSAI Architecture

The OBSAI reference architecture comprises of three reference points:

Reference Point 1 (RP1) interchanges control, performance, status, alarm and provisioning data between the Control and Clock Block and other BTS Blocks with the protocols specified in the RP1 specification document. RP1 also defines an open, standardized interface for exchange of clock and synchronization signals.

Reference Point 2 (RP2) interchanges user data between the Transport Block and the Base Band Block with the protocols specified in the RP2 specification document.

Reference Point 3 (RP3) interchanges formatted air interface user and fast control data between the Base Band Block and the RF Block with the protocols specified in the RP3 specification document.

NEC Electronic as OBSAI member

As a world wide top ASIC supplier, NEC Electronics delivers ASICs as important products to the mobile communications market. In base stations of the 3rd generation of mobile communication systems, running at high volume quantities and requiring a huge processing capability, such customized solutions offer optimized silicon at low cost. At NEC Electronics we are proud on our leading ASIC technology. But equally important we continuously expand our application specific solutions. This has been the motivation for NEC to join OBSAI and to work in direction to reach the targets of this initiative: to define module interfaces, interoperable between different manufacturers, that provide a cost advantage to the entire mobile industry and promote third-generation mobile phone systems.

OBSAI related solutions

As an ASIC supplier, it has been of major importance for NEC Electronics to offer OBSAI compliant macros for integration in ASIC products. On RP1 and RP2, standard Ethernet specifications are used. RP1 is control interface between main control block, transport block, baseband and radio module. RP2 is the data interface between transport block and baseband.

For these interfaces, NEC Electronics offers Ethernet MAC (Medium Access Control) macros and physical interface (PHY).For RP3, interfacing the processing and the radio units at high data transfer rates, OBSAI has defined XAUI-type Current Mode Logic (CML) transceivers. With the new SerDes (for serialization/de-serialization) macro NEC Electronics offers the function which is required for the high speed option of 1.536 Gbps. The macro includes multiple transmit units with a parallel to serial (P/S) converter, driver and multiple receive units consisting of Clock and Data Recovery (CDR), Serial to Parallel converter (S/P) and receiver. A common part integrates the PLL, bias generator and test logic, and controls up to 16 channels simultaneously. Additionally, the 8-bit/10-bit coders and decoders are available as macros to further complete the offer to ASIC designers.