ISM band Radio Frequency (RF) based radio is useful method for an object tracking when Mobile phone network has not a range. This paper describes shortly the study for using smart radio technologies in RF tracking systems. In that case the tracking means livestock, hound dog or human locating. The study presents some aspects how to approach a formulation of the problem. The paper describes architectures of software defined radio (SDR). One of the targets of study is to show that how software defined radio (SDR) could be a good choice in embedded tracking device.
Keywords: smart antenna, software defined radio, cognitive radio, WNS (wireless sensor network), tracking system, mobile phone network
Nowadays wireless technology is coming to our daily life more and more. Many of RF based location system have a traditional hardware based radio devices which limit cross-functionality and can only be modified through physical intervention. This causes in higher production costs and minimal flexibility in supporting multiple waveform standards. The radio transmitters and receivers have to get the best sensibility as possible in changing conditions as from bushy forest to open field, facing altitude changes etc. Applications can be like to locate death animals, locate the hound dog and for example the people tracking. In the defence industry the tactical communications, electronic warfare and signals intelligence solutions are based on SDR systems.
The cognitive SDR can be one solution for these challenges. SDR based solution can be a link to the other radio band, because frequency band is not fixed just for one. In the Cognitive SDR the cognitive Engine tells the radio how to control the knobs and meters. Basically, the cognitive radio learns from experience to control the parameters of radio engine. This study is focused to ISM band SDR solution. Main focus of the study is to present the SDR and CR functionalities.
This paper describes main principles of SDR and cognitive SDRs. Also overviews of SDR engine architectures will be shown in this paper. One aim of the study is to present the solution regarding with ISM band SDR. The study looking for the solutions are already done to integrate the workable software defined radio system. The Result and Discussion section goes through the results of the study. Discussion part kicks around the possibilities with positioning application on SDR.
2 Benefits of Software Defined Radios
Simply put Software Defined Radio is defined as:
"Radio in which some or all of the physical layer functions are software defined". The flexibility provided by the software allows a radio to interoperate with other devices using different wireless physical layer technologies, by simply using the appropriate software.
The transmitters can be fitted into wireless sensor network using 3g mobile based receiver as gateway to the internet. This enables to control devices and change their functional parameters remotely.
SDR defines a collection of hardware and software technologies where some or all of the radio’s operating functions are implemented through modifiable software or firmware operating on programmable processing technologies. These devices include field programmable gate arrays (FPGA), digital signal processors (DSP) programmable System on Chip (SoC) or other application specific programmable processors. The use of these technologies allows new wireless features and capabilities to be added to existing radio systems without requiring new hardware .
3 SDR and Cognitive SDR
A software-defined radio system, or SDR, is a radio communication system where components that have been typically implemented in hardware (e.g. mixers, filters, amplifiers, modulators/ demodulators, detectors, etc.) are instead implemented by means of software on a personal computer or embedded computing devices While the concept of SDR is not new, the rapidly evolving capabilities of digital electronics render practical many processes which used to be only theoretically possible .
Figure 1. SDR Architecture
3.2 Cognitive Radio (CR)
There are two major subsystems in a cognitive radio; a cognitive unit that makes decisions based on various inputs and a flexible SDR unit whose operating software provides a range of possible operating modes. A separate spectrum sensing subsystem is also often included in the architectural a cognitive radio to measure the signal environment to determine the presence of other services or users. It is important to note that these subsystems do not necessarily define a single piece of equipment, but may instead incorporate components that are spread across an entire network. As a result, cognitive radio is often referred to as a cognitive radio system or a cognitive network.
Figure 2. Architecture of CR engine
The cognitive unit is further separated into two parts as shown in the block diagram below. The first labelled the “cognitive engine” tries to find a solution or optimize a performance goal based on inputs received defining the radio’s current internal state and operating environment. The second engine is the “policy engine” and is used to ensure that the solution provided by the “cognitive engine” is in compliance with regulatory rules and other policies external to the radio.
4 ISM Band SDR
4.1 ISM Band Radio
The industrial, scientific and medical (ISM) radio bands are radio bands (portions of the radio spectrum) reserved internationally for the use of radio frequency (RF) energy for industrial, scientific and medical purposes other than communications. Examples of applications in these bands include radio-frequency process heating, microwave ovens, and medical diathermy machines.
Despite the intent of the original allocation, in recent years the fastest-growing uses of these bands have been for short-range, low power communications systems. Cordless phones, Bluetooth devices, NFC devices, and wireless computer networks all use the ISM bands.
Individual countries' use of the bands designated in these sections may differ due to variations in national radio regulations. Because communication devices using the ISM bands must tolerate any interference from ISM equipment, unlicensed operations are typically permitted to use these bands, since unlicensed operation typically needs to be tolerant of interference from other devices anyway .
ISM Band SDR solutions
GNU radio is one solution for software defined radio system. GNU Radio is a free & open-source software development toolkit that provides signal processing blocks to implement software radios. It can be used with readily-available low-cost external RF hardware to create software-defined radios, or without hardware in a simulation-like environment. It is widely used in hobbyist, academic and commercial environments to support both wireless communications research and real-world radio systems.
GNU Radio applications are primarily written using the Python programming language, while the supplied performance-critical signal processing path is implemented in C++ using processor floating-point extensions, where available. Thus, the developer is able to implement real-time, high-throughput radio systems in a simple-to-use, rapid-application-development environment. While not primarily a simulation tool, GNU Radio does support development of signal processing algorithms using pre-recorded or generated data, avoiding the need for actual RF hardware.
GNU Radio is licensed under the GNU General Public License (GPL) version 3. All of the code is copyright of the Free Software Foundation.
Figure 3. GNU Radio assembly
Hardware for GNU radio:
Hardware is strictly not part of GNU Radio, which is purely a software library. However, developing radio and signal processing code is even more fun when using hardware to actually transmit and receive, and GNU Radio supports several radio front-ends.
The most commonly used equipments are the USRP devices by Ettus Research, LLC.
GNU Radio can be used on its own without any hardware. GNU Radio has several blocks that can generate data or read/write from/to in different formats, like binary complex values or WAV-files. A lot of pre-recorded examples exist that can be used to develop applications without need for expensive hardware. Also, you can ask on the mailing list if anyone has some data available if it's a common waveform.
If you need to gather live real-world signals or output signals, several different possibilities exist:
Sound interface - cheap and easy
USRP - Opensource spinoff with RF frontends
Comedi - high quality framework for professional Data Acquisition and Output hardware
Most computers nowadays are shipped with a built-in sound interface or sound card. 16 Bit resolution at 44.1 kHz (kSPS) and two channels is a long available level that you can expect. Virtually every operating system supports this hardware out of the box, and it's sufficient for a lot of DIY and hobby applications. You can expect stereo (2 channels) input and output.
If the quality of a built in sound interfaces are not very expensively built and introduce noise or show bad frequency characteristics or degraded resolution, that is dynamic range. Fortunately, high quality sound interfaces are offered, like professional digital recording equipment, with more than a dozen channels, up to 24bit resolution and 192kHz sampling rate. These interfaces can be connected internally via PCI bus or externally via USB.
The USRP series by Ettus:
During the development of GNU Radio it turned out that no Open Source high speed interface was available. Ettus Research took to challenge to develop the Universal Software Radio Peripheral. The family of hardware grew, now including different motherboards with USB or Gigabit Ethernet interfaces, possible sampling rates up to 100 MSPS, a range of front-ends for reception and transmission from 0Hz up to over 5.8GHz, as PC bound device or as standalone embedded device.
5 Results and Discussion
ISM band based SDR solutions can be found. Most of SDR innovations have been done for cellular infrastructure. There are also thousands of software defined radios have been successfully deployed in defence applications.
In addition, the Wireless Innovation Forum’s market and technology studies have shown that cost effective radio frequency technologies supporting the operation of software defined radios over a broad spectral range have begun to mature.
For tracking purpose SDR based system suits well. When conditions are changed a possibility to control radio receiver gives more dynamics to application efficiency.
New features and capabilities to be added to existing infrastructure without requiring major new capital expenditures, allowing service providers to quasi-future proof their networks.
The use of a common radio platform for multiple markets, significantly reducing logistical support and operating expenditures.
Remote software downloads, through which capacity can be increased, capability upgrades can be activated and new revenue generating features can be inserted.
GNU Radio is a free & open-source software development toolkit that provides signal processing blocks to implement software radios. It can be used with readily-available low-cost external RF hardware to create software-defined radios, or without hardware in a simulation-like environment. Hardware is not included in GNU radio but GNU Radio supports several radio front-ends.
Using programmable technologies as FPGA, DSP, or SoC solution it allows new wireless features and capabilities to be added to existing radio systems without requiring new hardware.
From software aspect the solution can be found for smart radios. GNU radio is one solution. GNU Radio supports several radio front-ends. GNU Radio is a free & open-source software development toolkit that provides signal processing blocks to implement software radios.