Key words: 800/900MHz Application regulations Standard UHF Ultra-high frequency

1. Regulations for working frequency

Clause 1 in the Regulations: the specific useable frequency of the 800 MHz／900 MHz RFID technology is 840 MHz～845 MHz and 920 MHz～ 925 MHz.

The regulation for the frequency scope not only considers combining with the international standard, but also considers the actual situation of the division and industrial development of radio frequency in China and supports the research of the self-innovation RFID technology in China. The frequency scope is mutually combined with the international standard and can enable the RFID tag produced at home and abroad to provide conveniences for the export and circulation of the products made at home. At the same time, the RFID equipment produced by our manufacturers without any large modification can be used in America and Europe so as to reduce the enterprises’ design and manufacturing cost. The international standard of ISO/IEC18000-6 recommends that the frequency scope applied by the UHF RFID equipment shall be 860 MHz～960 MHz. Currently, the frequency plan made by main developed countries and regions in the world is shown as Table 1. The specific using situation for the frequency band of 860 MHz～960 MHz in China is shown as Table 2.

Table 1 Planning Situation of the World RFID Frequency

Table 2 Using situation for the frequency band of 860 MHz～960 MHz in China

From the using situation for the frequency band of 860 MHz～960 MHz in China (Table 2), we can see that the frequency within the frequency band has been divided and there is no surplus frequency band applied for the RFID frequency, so it is necessary to choose the working frequency that has little influence on the existing business. The mobile communication and aerial navigation business have a wide useable area and is quite important, so the state is difficult to take measures to realize the sharing of RFID business. The centerless intercom business is a kind of narrowband business and its useable frequency range width is only 2 MHz, so it is difficult to take the sharing method to do the RFID business. Therefore, our country adopts the method of making the RFID business and the point-to-point stereo broadcasting transmission business share the same frequency band. The point-to-Point stereo broadcasting transmission business is mainly applied for the programme transmission between the broadcast station broadcasting center and the frequency modulation broadcasting transmission machine room at a frequency band of 917 MHz～925 MHz. The author thinks that the national ~BRFtD useable frequency planned within 920 MHz～925 MHz shall be considered from the following aspects:

Secondly, along with the development of optical fiber communication and satellite communication, most of the original point-to-point stereo broadcasting transmission business has already been replaced by the optical fiber communication or satellite transmission. Along with the reduction of its application, the useable frequency of this kind of business can be gradually adjusted to this scope of 917 MHz～920 MHz.

Thirdly, the useable frequency band in Hong Kong is also 920 MHz～925 MHz. The consistency of the scope selection is beneficial to speed up the application of RFID technology in the rapid circulation of Guangdong-Hong Kong goods.

White paper on China RFID technology policy points out: “Establish the self-innovation system for China RFID technology and acquire the proprietary intellectual property rights of the core technology. Our country has divided double frequency band for the useable frequency of RFID, but also has divided the frequency band of 840 MHz～845 MHz for use from the 800 MHz frequency band except the frequency band of 920 MHz～925 MHz. This kind of division fully considers that the future development of RFID industry has a sufficient frequency expansion space, but also supports the research in self-innovation RFID technology. At first, although the opportunity for the domestic and foreign RFID equipment manufacturers is equal to this kind of RFID product at this frequency band in terms of intellectual property rights and product production, the RFID equipment at this frequency band can only be used at home. This means a greater advantage for the domestic manufactures to acquire the proprietary intellectual property rights of the core technology. Secondly, the division of the double frequency band considers the balance toward Europe and America, but also gives attention to the European and American market. The 900 MHz RFID equipment produced and used at home can be sold to America through small modification of the software and the 900 MHz RFID equipment can be sold to Europe through small modification.”

The division of double frequency band also has some deficiencies. At first, as the radio frequency component of the RFID equipment that supports double frequency have a higher requirement than that supports single frequency, requiring the broadband and high dynamic scope, the research and development cost and manufacturing cost for the manufacturers will be relatively high. Secondly, if the RFID reader with the frequency band of 840 MHz～845 MHz reads the RFID tag with the frequency band of 920 MHz～92 5 MHz, the biggest reading and writing distance has about 30% loss that results from the power loss brought by the non-broadband characteristics of the radio frequency components such as the filtering component and antenna of the RFID and RFID reader.

2. Regulations for the occupied bandwidth

Compared with the other countries and regions in the world, the RFID channel bandwidth regulated by Europe and America is respectively 200 kHz and 500 kHz. The occupied bandwidth is jointly decided by the data transmission speed and modulation mode so as to regulate the data transmission speed and modulation mode, so the needed occupied bandwidth is correspondingly confirmed. Under the circumstances that the modulation mode is fixed, the data transmission speed will be faster. However, the data transmission speed is related to the information length and coding mode of RFID tag and tag readable times per minute. The modulation mode that shall be used by our RFID equipment is not clearly pointed out in Regulations. Under normal circumstances, the UHF RFID equipment takes ASK modulation as main stream and is divided into the types of DSB-ASK SSB-ASK and PRASK. In theory, the minimum bandwidth occupied by the data signals under the modulation of DSB-ASK is 4 times than that of the data transmission speed; the minimum bandwidth occupied by the data under the modulation of SSB-ASK is 3 times, while the minimum bandwidth occupied by the data under the modulation of PR-ASK is 2 times. In the ISO1 8000-6 standard, both Type A and Type B require that the data transmission speed of the return link shall be 40k bit/s. According to the theoretical calculation, the essential occupied bandwidth shall be 80 kHz, 120 kHz and 240 kHz respectively. As for our country, the 250 kHz occupied bandwidth is enough to meet the need of data transmission speed.

Clause 2 in the Regulations: the channel bandwidth and the occupied bandwidth of the channel (99% energy): 250 kHz.

3. Regulation for the transmission power

Clause 5 in the Regulations, the regulation for the transmission power is shown as Table 3.

Table 3 Regulation for the transmission power

Table 4 Transmission power regulated by other countries and regions

The largest transmission power regulated by other countries and regions in the world is shown as Table 4.

By comparing the largest transmission power in China with that in other countries or regions, we must make certain about two issues. The first is the difference and relation between the e.i.r.p and the e.r.p; the second is to make clear the relation between the RFID equipment’s reading distance and transmission power. e.i.r.P(Effective Isotropic Radiated Power) refers to the effective omnidirectional transmission power. Compared with the omnidirectional antenna, it means that the transmitter can acquire the transmission power in the largest antenna gaining direction. e.r.P(Effective Radiated Power) refers to the effective transmission power and means the largest transmission power if it is compared with the semiwave dipole antenna. The relation between them is: e.i.r.p=e.r.p+2.15dB. Our country regulates that the largest transmission power of e.r.p is 2W, namely 33dBm. It is assumed that the gain of the used antenna is 10dBi, we can get that the largest allowable power of the transmitter port is: Pt=33+2.1 5-10 =25.15d8m, about 330mW. The reading distance of the RFID equipment has a certain relation with the transmission power. The theory proves that the reading distance of the RFID reader to the tag shall abide by the radar equation, namely:

In the equation, Pr refers to the receiving power of the reader; Pt refers to the transmission power of the reader; G is the gain of antenna; λ is wavelength; σ is the sectional area of the radar scattering; R refers to the reading distance. This equation indicates that the reading distance of RFID equipment is in inverse proportion to the fourth root of the transmission power. In other words, if you want to double the reading distance, you must increase the transmission power by 16 times under the circumstances that other situations are not changed. This indicates that it is very difficult to increase the reading distance by increasing the transmission power. Although the largest transmission power regulated by our country is lower the numerical value regulated by other countries and regions, it has little influence on the reading distance. In addition, we can see from Table 3, in order to prevent from causing interference to the radio business at the adjacent frequency bands, the state has divided two channels at the front and rear ends of the two frequency bands as the isolation channel and regulated that the largest transmission power shall be 200mW.

4 Regulation for working mode

Clause 6 in the Regulations: the working mode is the mode of Frequency Hopping Spread Spectrum and the largest residence time per frequency hopping is 2 seconds.

The largest advantage of the working mode of the Frequency Hopping Spread Spectrum is that it has stronger interference resisting capability, but also it has the advantages of strong confidentiality and anti-multipath interference. In America, the RFID frequency scope divided to the UHF frequency band is 902 MHz～928MHz, totally 26 MHz. As this frequency band is the ISM frequency band, the working mode of the Frequency Hopping Spread Spectrum must be adopted to resist interference.

The frequency band of 920 MHz～925MHz divided to the RFID equipment in China shall be shared with the point-to-point stereo broadcasting transmission business, so the measure of Frequency Hopping Spread Spectrum is also adopted to reduce interference. The Regulations don’t regulate the minimum residence time, because the minimum residence time is only related to the reading quality of the reader and shall be individually controlled by the equipment manufacturers. As the maximum residence time is too long, it may cause the mutual interference between the equipment and the radio business at other shared frequency bands, so the Regulations regulate that the maximum residence time shall be 2 seconds.

5. Conclusion

The issue of the Regulations greatly promotes the development of China RFID industry, but also brings new challenges for our radio management department. How to guide it soundly and stably developing towards the correct direction when a new radio business begins to develop is a subject that shall be considered by the radio management department.

References

[1] Regulations (Trial basis) of the 800/900MHz RFID Technology Application (X.B.W [2007] No.205);

[2] White paper on China RFID technology policy issued by the fifteen ministries and commissions such as the Ministry of Science and Technology of the People’ Republic of China;

[3] Series of ISO/IEC 18000 standards: Information technology-Radio frequency identification for item management；

[4] RFID technology and related EMC study, written by Song Qizhu and issued by the State Radio Monitoring Station;

[5] Report about the China RFID system frequency plan and the system simulation for the mutual interference between the RFID system and other radio communication systems, written by Min Hao in Fudan University;

[6] Suggestions and key research problems for the RFID standard system, written by Zhu Yanghe and Liu Haixiao.