World’s First Portable Tablet Terminal in TV White-space

- High-speed Communications by Automatic Utilization of Available White-spaces -

August 28, 2013

The National Institute of Information and Communications Technology (NICT, President: Dr. Masao Sakauchi) has developed the world's first portable-size tablet terminal that enables radio communications in TV bands (470-710 MHz). This tablet terminal utilizes the WLAN systems for the radio communications in TV bands with an inquiry in the white-space database developed by NICT. Original 2.4 GHz band of WLAN system is also available and it is possible that the tablet terminal automatically selects the radio communication band according to the data traffic, etc. by the control of the network manager. The white-space utilization by portable devices achieves not only the fixed point communications but also the mobile communications, and contributes to the further effective use of frequency resource.

Background

Due to the explosive growth of mobile portable devices such as smart phones and tablet terminals, communication traffic has been getting more and more increased and a frequency resource shortage problem has been aggravated. To solve this problem, a utilization of TV white-space has been studied and the establishment of radio rules designed for TV white-space operation has started in　the U.S., the U.K., etc. NICT has contributed to standardization on various radio communication systems utilizing TV white-spaces, and has developed stationary prototypes based on the standards. Although future TV white-space utilization by portable devices contributes to the further effective use of frequency resource, it was difficult to miniaturize components and circuits for portable devices due to its lower operational frequency than existing WiFi or cellular bands, its relatively wide frequency range of 470-710 MHz, and its requirement of implementation of interference avoidance technology to TV broadcasts. On the other hand, the propagation characteristic evaluation supposing practical operation is required for the feasibility study on TV white-space utilization.

Achievements

A prototype of the tablet terminal in TV white-space.

NICT has developed the world's first portable-size Android tablet terminal that enables radio communications in TV bands. This tablet terminal is originally based on an off-the-shelf terminal and a frequency converter newly developed by NICT is implemented for utilizing TV white-spaces. Radio communications in both TV and 2.4 GHz bands is available with original WLAN system (IEEE802.11b/g) and Internet access is also possible through the white-space WLAN base station developed by NICT. In addition, this tablet terminal can operate in the frequency considered not to interfere with TV broadcasts according to calculation results provided by the white-space database developed by NICT, and can automatically select the optimal frequency according to the data traffic, etc. by the control of the network manager.

Some other functions implemented in this tablet terminal are:

1. Display function of the white-space availability of each channel and the terminal location on a map, by acquiring primary users (TV broadcasters) information from the white-space database.

2. Power control function for the different limitation of the output power according to the white-space status such as a location and time.

Future prospects

Mobile communications in TV white-space have many subjects. For example, a white-space judging method for avoiding the interference to TV broadcasts is required. NICT will perform an evaluation of the propagation characteristic using this tablet terminal and offer the information that contributes to a technical reference and a rule designed for TV white-space operation. Furthermore, NICT continues to contribute to the standardization activities of wireless communication systems utilizing TV white-spaces and promote a development of portable devices based on such standardized communication systems by applying elemental technologies implemented in this tablet terminal.

Appendix

Prototyped tablet terminal

Prototyped tablet terminal (Fig. 1) is originally based on an off-the-shelf tablet terminal, and a UHF converter newly developed by NICT and a control board are additionally assembled inside. To simply realize a WLAN-based communications in TV white-spaces, a native communication band of the built-in WLAN module is converted to the UHF band by the UHF converter (Fig. 2). This is the world's first portable-size tablet terminal prototype that enables radio communications in TV bands. Supported communication system in TV bands is IEEE802.11b/g, and commercial 3GPP network and original WiFi system in 2.4 GHz are also available.

For the communications in TV white-spaces, this tablet terminal can connect to the white-space WLAN base station developed by NICT. Therefore, internet access through the mesh network that consists of a number of the white-space WLAN base stations in TV white-spaces is also available (Fig. 3). In addition, both TV white-space and 2.4 GHz are available and it is possible that the tablet terminal automatically selects a radio communication band according to the data traffic, etc. by the control of the network manager.

Table 1 shows main features of the prototyped tablet terminal. Since GPS is supported, this terminal can display the white-space status of each channel and the terminal location on a map (Fig. 3), by acquiring primary users (TV broadcasters) information from the white-space database developed by NICT. In addition, this terminal can be operated by the battery for several hours without any external power source.

Fig. 1 A prototype of the tablet terminal (left) and the white-space WLAN base station (right).

Fig. 2 Brief architecture of the tablet terminal.

Table 1 Main features of a prototype of the tablet terminal

Item	Specification
Display	10.1 inch 1366 × 768
Cellular	HSPA+/WCDMA/GSM/GPRS/EDGE (mini PCI Express)
WiFi	802.11b/g/n (2.4 GHz)
GPS	Built-in standalone receiver
Camera	Front 1.3 Mega pixel Rear 3 Mega pixel
Power	5 V, 2A Battery 3.7 V/9000 mAh (Lithium Polymer)
OS	Android2.3
Size	268(L) × 170(W) × 35(H) mm³

©NICT

Fig. 3 Network architecture operated in TV white-space with a prototype of the tablet terminals.

Glossary

White-space database

White-space database is defined as a device or a function which provide available channels or frequencies as white-spaces for secondary users by calculation based on a certain rule, according to the primary user status such as an installation location, frequency and transmission power and geography information. In Japan, it is expected that an argument about a calculation rule of the interference and information of secondary users operation, will be made from now on.

The white-space database developed by NICT was press released as below. (6/7/2012)
　URL : https://www.nict.go.jp/en/press/2012/06/07en-1.html

White-space WLAN base station

White-space WLAN base station was developed by NICT and can operate in TV white-spaces (470-710 MHz). A mesh network can be also formed by a number of these base stations. This base station support IEEE802.11af Draft 2.0 and existing WiFi systems, i.e. IEEE802.11a/b/g, and thus, it can be operated as a base station for the prototyped tablet terminal.

The white-space WLAN base station was press-released as below. (10/17/2012)
　URL : https://www.nict.go.jp/en/press/2012/10/17-1.html