Figure 14 Code resolution flow chart based on mobile RFID middleware
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To eliminate the analogue component from the design, it is necessary to prepare corresponding wireless specifications for it. This section prepared the domestic wireless specifications for mobile RFID in Korea, in reference to applicable RFID frequency, cell radius, channel allocation and relevant radio regulation acts (ordinances), technical standards, etc. (Lee et al., 2006). For a mobile terminal with an RFID reader embedded, the configuration of reader chip and adjacent circuitry can be illustrated as shown in Figure 1. Inside the reader chip are two components: the digital component, which processes host/RFID protocols, and the analogue component, which processes base band signals and 900 MHz RF signals. The tolerance of transmit frequency sent from mobile RFID should be set to less than +10 ppm in a temperature of —25°C to +40°C and up to +20 ppm in a temperature of — 40°C to +65°C. The modulation method of a mobile RFID should be either DSB-ASK, SSB-ASK or PR-ASK. When a mobile RFID uses one of the designated modulation methods specified above, the occupied frequency bandwidth of each channel must be below 200 KHz. When RF signals transmitted from a mobile RFID occur during power- up or power-down, they create envelope waves depicted in Figure 2. The factor value related to the envelope shape according to time belongs to the norms shown in Table 2. 1 Channel no. and channel band according to frequency allocation of mobile RFID able 2 Envelope wave parameters of transmit signal Figure 2 Envelope wave of transmit signal able 3 Channel selectivity of mobile RFID receiver 2.3.2 Classes of mobile RFID technology For realisation of mobile RFID services, it is required that RFID devices such as RFID tag or RFID reader should be installed within mobile phones. The Nokia supports RFID technology based on 13.56 MHz, MIFARE™ UltraLight, and ISO 14443A. Another mobile phone with RFID functions, the Nokia 3220, is released to public. This Nokia 3220 is based on NFC protocol that uses 13.56 MHz complying with ISO/IEC 18092. The Nokia 5140 and 5140i phones as well as 3220 phone with the integrated Xpress-on™™ RFID reader shell are capable of launching services and access phone functions such as dial or send messages by touching an RFID tag. The mobile phone users can automate and initiate tasks, such as browsing service instructions or logging time-stamped data like metre readings (Nokia, 2004). KDDI in Japan developed slide-in RFID readers that can be easily attached to the backside of a mobile phone. There are two types of RFID reader according to frequency band. One is 2.45 GHz passive type and the other is 315 MHz active type. Some pilot Figure 5 Network architecture model of KDDI’s mobile RFID service lable 4 Summary of mobile RFID implementations As shown above, UHF-band mobile RFID uses 908.55—913.95 MHz and complies with ISO/IEC 18000-6 Types B and C (Chae and Oh, 2005; Garfinkel and Rosenber, 2005; Park et al., 2006a). From the viewpoint of service deployment, the UHF-band is more profitable according to the following observations: Figure 6 Conceptual network model for mobile RFID service The mobile RFID service structure is defined to support ISO/IEC 18000-6 A/B/C through wireless access communication between the tag and the reader; however, as yet there is no RFID reader chip capable of supporting all three wireless connection access specifications so that the communication specification for the mobile phone will be determined by the mobile communication companies (Chae and Oh, 2005; Sakurai and Kim, 2006; TU-T TSAG, 2006). It will also be possible to mount the RF wireless communication function on the reader chip using Software-Defined Radio (SDR) technology and develop an ISO/IEC 18000-6 A/B/C communication protocol in software to choose from the protocols when needed. Figure 7 Block basic communication scenario for mobile RFID service Figure 8 Detailed mobile RFID’s code resolution process 3.2. Data communication structure Table 5 RFID tag functionality classes Tag readers interrogate tags for their data through an RF interface. To provide additional functionality, readers may contain internal storage, processing power or connections to back end databases. Computations, such as cryptographic calculations, may be carried out by the reader on the behalf of a tag. The channel from reader-to-tag may be referred to as the forward channel. Similarly, the tag-to-reader channel may be referred to as the backward channel. Figure 9 The mobile RFID reader (see online version for colours) Figure 10 Architecture of RFID extended mobile embedded platform The software architecture is composed of REX OS, WIPI HAL (Handset Adaptation Layer) API, WIPI Runtime Engine (WRE), WIPI C API, phone application, browser parser and phone GUI. Most functions for mobile RFID technology are designed in the WIPI C API: they are reader control, tag control, buffer control and filter control for interfacing with the RFID reader; and code decoder, URN converter, Fully Qualified Domain Name (FQDN) converter, DNS resolver and connect contents server for communicating with a local ODS server and the contents web server. Figure 11 Block diagram of the mobile platform for networked RFID Figure 12 Block diagram of the UHF band mobile RFID reader (see online version for colours) Figure 13 Function block diagram of mobile RFID middleware platform in the mobile phone Figure 15 Scenario of secure mobile RFID M/W terminal function Figure 16 Proposed secure mobile RFID middleware's development (see online version for colours) Figure 17 Arch. of portal discovery service gateway system The gateway provides the privacy protection method to the RFID user by making the RFID tag with personalised one. By changing the original code value into new one, only the user who knows the original code value can get the contents of the tag. The gateway system manages code recoding technique by managing the lookup table values. In this case, only he authorised user can access the loo enhancing capability is due to our proposed mechanism, so ca Service (RPS). This mechanism is in the process of international standardisation at ITU- T (Park and Lee, 2004). T kup table. led the R he RPS mainly consists of three components suc Profile Processing (PPP) controller, which controls the main o peration o of the code The privacy FID Privacy h as Privacy f RPS, RPS decision agent, which adapts the privacy and audit policy profile to all RFID participants and decides the level of security in each transactions, OIS sc manages and updates the schema values of the RPS. nema man ager, which ODS resolver function: In the mobile RFI D service environment, the ODS server carries out ‘code resolution’ to look for URI information regarding an RFID code. According to the ODS communication protocol, the O DS resolver gains the URI of the information resources related to the code and then sends it to the mobile RFID application. User’s communication fees depend on what information system contains this ODS resolver. That is the ODS resolver may be installed within the mobile phone or in the local ODS server of the telecom company. It is high chooses the latter. yy recommended that the mobile RFID service The mobile RFID service has the least ODS resolver function within a mobile phone, the stub ODS resolver, which sends a query on a code to the ODS server of the telecom company from the mobile phone application. The ODS server plays the role of functions as the ODS resolver, performing code resolution with the root ODS first and other ODS servers according to the ODS hierarchy. The ODS resolver of the telecom company transmits the final URI information to the stub ODS resolver within the mobile phone and in turn the information is delivered to the application. Through this mechanism, the mobile RFID application within a mobile phone calls for code resolution through a one- time ODS query and receives are response message wherein communication traffic occurs much less than when the ODS resolver of the phone carries out the function itself the function (Park et al., 2005; Park et al., 2007). Figure 19 Conceptual architecture of secure mobile RFID service framework The main functions of the proposed service model are the provision of WIPI-based mobile security middleware, tag authentication, tag tracking prevention, reader authentication, message security, non-traceable payment and policy-based privacy protection (Ohkubo et al., 2003; Mobile RFID Forum of Korea, 2005a; Park, 2008). Figure 20 Architecture crypto library in mobile middleware Below is the method of reinforcing RFID data communication security service by using crypto algorithm based on mobile phone terminal platform in mobile RFID service. The mobile RFID crypto library is a crypto library for the efficient processing of the crypto algorithms and security protocols. It provides security mechanisms to the mobile RFID reader and targets the mobile RFID middleware based on the WIPI platform. The mobile Figure 21 Service structure of mobile RFID crypto library 7 Conclusions Figure 22 Crypto algorithm's GUI in mobile RFID middleware (see online version for colours)
