The NFC Forum has announced the release of two candidate specifications that further the integration, implementation and standards interpretation of NFC technology.
The NFC Digital Protocol specification addresses the digital protocol for NFC-enabled device communication, providing an implementation specification on top of the ISO/IEC 18092 and ISO/IEC 14443 standards. It harmonizes the integrated technologies, specifies implementation options and limits the interpretation of the standards; in essence, showing developers how to use NFC, ISO/IEC 14443 and JIS X6319-4standards together to ensure global interoperability between different NFC devices, and between NFC devices and existing contactless infrastructure.
The NFC Digital Protocol specification defines the common feature set that can be used consistently and without further modification for major NFC applications in areas such as financial services and public transport. More specifically, the specification covers the digital interface and the half-duplex transmission protocol of the NFC-enabled device in its four roles as Initiator, Target, Reader/Writer and Card Emulator. The specification includes bit level coding, bit rates, frame formats, protocols, and command sets, which are used by NFC-enabled devices to exchange data and bind to the LLCP protocol.
The NFC Logical Link Control Protocol (LLCP) specification defines an OSI layer-2 protocol to support peer-to-peer communication between two NFC-enabled devices. This is essential for any NFC applications that involve bi-directional communications. The specification defines two service types, connectionless and connection-oriented, organized into three link service classes: connectionless service only; connection-oriented service only; and both connectionless and connection-oriented service.
The connectionless service offers minimal setup with no reliability or flow-control guarantees (deferring these issues to applications and to the reliability guarantees offered by ISO/IEC 18092 and ISO/IEC 14443 MAC layers). The connection-oriented service adds in-order, reliable delivery, flow-control, and session-based service layer multiplexing.
LLCP is a compact protocol, based on the industry standard IEEE 802.2, designed to support either small applications with limited data transport requirements, such as minor file transfers, or network protocols, such as OBEX and TCP/IP, which in turn provide a more robust service environment for applications. The NFC LLCP thus delivers a solid foundation for peer-to-peer applications, enhancing the basic functionality offered by ISO/IEC 18092, but without impacting the interoperability of legacy NFC applications or chipsets.
“As more NFC devices and applications come to market, it is essential that we ensure their smooth interoperability with earlier NFC implementations and existing contactless infrastructure such as ISO/IEC 14443 and FeliCa,” comments Koichi Tagawa, chairman of the NFC Forum. “These two specifications are significant because they establish clear and well-defined parameters for the implementation behavior of NFC devices and applications, thereby providing this needed assurance.”