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Software Radio -Abhishek Banerjee -Vivek Gaddipati
Agenda n n n n Problem – Solution Software Radio Defined SDR History Why we need Software Radio Applications SDR Architecture & Programmability Technological Challenges Security Implications Advantages and Disadvantages Conclusions References and Further Reading Quiz Vivek Abhishek
The Problem - Interoperability n Northern Iraq: US Navy jets mistakenly attacked a Kurdish convoy led by US Special Operation Forces. Caused by a simple mix-up: the radios carried by the SOF were compatible only with USAF aircraft but not with US Navy jets which had attacked them! n September 11: Hundreds of firefighters and police officers rushed into the World Trade Center. Helicopters circling overhead noticed the buildings starting to glow and relayed to incident commanders on the ground that the buildings may collapse. The police officers were given the order to evacuate --- all but 80 escaped. The firefighters never got the word --- 121 of them, most within striking distance of safety, never got the word
The Solution: Software Defined Radio
What is Software Radio? • Software radio is the art and science of building radios using software. • The idea is to get the software as close to the antenna as is feasible • By radio, I mean any kind of device that intentionally transmits or receives signals in the radio frequency (RF) part of the electromagnetic spectrum. Examples: -phones and cordless phones, Garage door openers, Car door openers, Wireless internet cards (Wi. Fi / 802. 11), pagers, GPS, the list goes on and on.
SDR - History n increased attention during second part of 1990 -ies n MMITS formed by US government, for converging the multiple radio interfaces and systems in defense area n MMITS changed name and scope to SDR Forum n In Europe, the CEC took several initiatives to promote and boost SDR development. n Standard architecture (SCA) Published by Joint Tactical Radio System (JTRS) Joint Program Office (JPO)
The SDR Forum · Open, non-profit corporation created in 1996, to develop technical specifications and standards requirements that meet the diverse requirements for commercial wireless, defense, and civil government applications of SDR · International membership and alliances, over 70 organizations: - equipment manufacturers (infrastructure and user terminals) - component manufacturers - hardware and software developers - regulatory agencies · service providers/ network operators academic and research organizations Permanent staff established March 2000 to support growing level of participation from predominantly commercial members
Why we need Software Radio 1/2 n Enables the creation of open APIs for the radio interface and reduces the number of radio components. n This is very useful to increase the battery life and make the seamless operations simpler. Intelligent terminals may benefit a lot of the multimode features. For ex: there is no reason to deliver High Quality TV picture via Cellular networks if TV broadcasting can be utilized. n They can be quickly and easily upgraded with enhanced features.
Why we need Software Radio 2/2 n They can be reconfigured "on-the-fly". That is, depending on what you need, your universal communication device would reconfigure itself appropriately for your environment. Example: -It could be a cordless phone minute, a cell phone the next, a wireless internet gadget the next, and a GPS receiver another. n Smart radios or cognitive radios can look at the utilization of the RF spectrum in their immediate neighborhood, and configure themselves for best performance n Software radio makes it feasible to implement many of the complementary advances in wireless technology that have occurred in recent years, including smart antennas, adaptive power management, or new modulation and signal processing techniques.
Future with Software Radio
Value added to the chain
Where can we use SDR ? n Base Stations ¨ Weak constraints on power and area ¨ Support several hundred subscribers ¨ Will be commercialized first n Wireless terminals ¨ Tight constraints on power and area. ¨ Will be commercialized next
Applications n The military has been interested in software radio for some time, and not surprisingly, some of the first implementations have been in military applications. n Telematics (i. e. use of computing and communications in vehicles) will be one of the earliest commercial applications of software radio. n Wireless service operators and equipment manufacturers are also interested in software radio. n Software radios hold great promise for wireless consumer devices because they can facilitate meeting form factor and convenience goals
SDR in military applications 1/2 n Goals: – To enable and improve the efficiency of joint operations (co-operation between separate troops) n Interoperability (connections between different systems). – Implementation of new features and systems without the need to purchase new equipment. – Reduce the number of radios. US armed forces has 25 – 30 radio families in use. – Flexible services (adaptive waveforms).
SDR in military applications 2/2 n Joint tactical radio systems – JTRS – US military software radio program. – Family of common Radios and Waveforms built around a standard open architecture. – New radios of US armed forces must fulfill JTRS requirements. • Radios must be based on SCA-architecture.
SDR in civil applications n State of software radio: n • • • n n – The role of software radio in civil applications is not clear yet. Some possible applications: Next generation multimedia satellites Only (economical) way to introduce new services or systems to orbiting satellites. Implementation of 4 G-terminals. The same terminal or base station can operate in several different systems. Reconfigurable multi-standard terminal for heterogeneous networks.
Emerging SDR uses n Personal communication devices ¨ Cellular n / Paging / Wireless LAN(s) PC based “generic transceiver” ¨ Radio / TV ¨ Emerging unlicensed RF band apps
SDR Generic Architecture • Common Hardware / Open Architecture • Commercial Level Cryptography • SEI/SCA Based Software Architecture OSIL/CORBA implementation Multiple functionality and performance in the presence of failures
HW/SW Thread View
Software Design Approach Software Common Architecture (SCA) Approach defined Interfaces enable the independence of SW Well modules. Operating System Isolation Layer (OSIL) n q q q Modifications to SCA approach based on routing of secure data Isolation of key data Paths No multi-tasking of processors to ensure security measures are implemented
HW/SW Processing View
SCA n 1/4 The Software Communications Architecture (SCA) specification establishes an implementation independent framework with baseline requirements for the development of software configurable radios. • These requirements are comprised of interface specifications, application program interfaces (APIs), behavioral specifications, and rules. • The goal of this specification is to ensure the portability and configurability of the software and hardware and to ensure interoperability of products developed using the SCA. • Open standard. n Currently the most advanced (and only) open standard developed for the software radio.
SCA 2/4 n Bus Layer (Board Support Package): – The Software Architecture is capable of operating on commercial bus architectures. Possible buses include VME, PCI, Compact. PCI, Firewire (IEEE-1394), and Ethernet. n Network & Serial Interface Services: – The Software Architecture relies on commercial components to support multiple unique serial and network interfaces. n Possible serial and network physical interfaces include RS-232, RS-423, RS-485, Ethernet, and 802. x.
SCA 3/4 n Operating System Layer: – The Software Architecture includes real-time embedded operating system functions to provide multithreaded support for applications. The architecture requires a standard operating system interface for operating system services in order to facilitate portability of applications. Specification defines a minimal POSIX profile to meet SCA requirements. n Core Framework: – The CF is the essential (“core”) set of open application-layer interfaces and services to provide an abstraction of the underlying software and hardware layers for software application designers.
SCA n n 4/4 CORBA Middleware: – CORBA is used in the CF as the message passing technique for the distributed processing environment: Application Layer: – Applications perform user communication functions that include modem-level digital signal processing, linklevel protocol processing, network-level protocol processing, routing, external (I/O) access, security, and embedded utilities. Applications are required to use the CF interfaces and services.
Hardware view of Software Radio
SDR Architecture Advantages Common Assets capable of performing any of the functions in the radio Common hardware Open Architecture Software Modularity Graceful Degradation in failure conditions Open Architecture features allow additional functionality to be added with minimal impact n
Programmability 1/3 n n n Programmable components: – General purpose processors – DSP-processors – FPGAs – ASSP-processors (e. g. in filtering) – Tunable RF-circuits Modular design. Plug and play modules to add new HW resources or to replace old ones with more capacity.
Programmability 2/3 Hardware radio n no software changes Software controlled radio n in PDR, BB operations and link layer protocols are implemented in software. Software defined radio n SDR system is one in which the BB processing as well as DDC/DUC modules are programmable. PDR - programmable digital radio DDC/DUC, digital BB, baseband down/up converter
Programmability 3/3 Ideal software radio n programmability is extended to the RF section Ultimate software radio n in a single chip, no external antenna and no restrictions on operating frequency n intended for comparison purposes only
What is GNU Radio? It’s a free software defined radio n A platform for experimenting with digital communications n A platform for signal processing on commodity hardware n Transmit and receive any signal n Create a practical environment for experimentation & product delivery n Expand the “free software ethic” into what were previously hardware intensive arenas n
Software Radio Networking n n n Software radios acting as nodes in a network. Software radios acting as gateways or bridges between networks. Software Radio Network is in the nature of a Adhoc, Multi-Hop, Self-organizing Network. OSI protocol architecture includes layers : Physical, Data Link, Network, Transport and Application. Issues are : Scalability Security Support for different protocols.
Technological challenges 1/3 n Data converters are one of the key enabling technologies. ¨ Dynamic range of wideband, high-speed A/D-converters is perhaps the most limiting factor in software radio implementation. ¨ Superconductor technology can be used to improve A/Dconverter performance ¨ With current technology it is possible to produce over 20 effective bit A/D-converters that operate at 2 GHz center frequency and have bandwidth of 60 MHz. ¨ Converter with 400 MHz bandwidth at 5 GHz center frequency and 10 – 12 bit resolution is under development. ¨ Need for low temperatures, 5 K cooler will require about 500 cubic inches and 100 – 150 W.
Technological challenges 2/3 n In portable devices power consumption is a critical issue. ¨ Fast data converters and powerful (high clock frequency) processors need more power than slower ones. ¨ Applications (e. g. image processing) need processing capacity. ¨ A/D-processing at low IF-frequency or at base band. ¨ Analog down conversion and filtering. ¨ Multi-band, multi-signal operation by integrating separate RF-chains into a chip, MEMS-technology can be used to implement filter banks and tunable circuits.
Technological challenges 3/3 Other challenges -DSP ¨ Several simultaneous connections. • Different sample rates needed for different systems. ¨ Implementation of new features and new systems ¨ All signal processing with programmable components • DSP vs. FPGA. ¨ Need of computation resources • How much is enough? • How to reckon with future computation needs? ¨ Allocation of computation resources between applications • Dynamic allocation in changing situation. • How to ascertain that all applications have enough computing resources?
Software issues n n Software components ¨ Operating system ¨ DSP-function/algorithm library ¨ Network function/algorithm library ¨ Applications/interfaces to applications ¨ User interface Addition of new features Software reuse ¨ Same software in different equipments Development of general architecture requires modeling of the architecture using some formal method ¨ Comparison between alternatives ¨ Design and testing of control structures ¨ Administration of updates
SDR Security 1/3 SDR’s used will require at least commercial cryptography to prevent the networks from penetration Hi-Jack Anti Spoofing Anti Positive Identification of participants n
SDRForum classifies the collection of software for SDR as follows: Security 2/3 The SDR n Radio Operating Environment - consists of the core framework, the operating system, device drivers, middleware, installer and any other software fundamental to the operation of the radio platform. n Radio Applications - software which controls the behavior of the RF function of the radio. This includes any software defining the air interface and the modulation and communication protocols. It also includes used to manage or control the radio in a network environment. n Service Provider Applications - software used to support network and other service provider support for the user of the radio. It includes voice telephone calls, data delivery, paging, instant messaging service, video pictures, emergency assistance, and geolocation. n User Applications - application software not falling into any of the above categories.
SDR Security 3/3 n n n Security threats from programmability of RF parameters such as modulation, frequency and power. Unauthorized modification of radio function can be avoided by ensuring separate processes, trusted and policy driven configuration. Protect memory access by software based fault isolation techniques.
Advantages of SDRs Communicators across the globe are now in a position to enjoy the advantages of SDRs. Desirable characteristics include, but are not limited to: a) the ability to receive and transmit various modulation methods using a common set of hardware; b) the ability to alter functionality by downloading and running new software at will. c) the possibility of adaptively choosing an operating frequency and a mode best suited for prevailing conditions; d) the opportunity to recognize and avoid interference with other communications channels; e) elimination of analog hardware and its cost, resulting in simplification of radio architectures and improved performance; and f) the chance for new experimentation.
Disadvantages of SDRs While SDRs offer benefits as outlined above, a few obstacles remain to their universal acceptance. Those include: a) the difficulty of writing software for various target systems, b) the need for interfaces to digital signals and algorithms, c) poor dynamic range in some SDR designs, and d) a lack of understanding among designers as to what is required. e) Complex Networking protocols required f) Huge efforts in standardization and regulation g) Opens up great security implications.
Conclusions SDR contains large number of areas that require significant research Hardware n Improving functionality to support additional flexibility Operating Environment n Standardize functionality and interfacing to support problems directly relevant to radio design n Power sensitive environments Network n Develop applications that can break the previous approaches for the management of resources and take full advantage of capabilities of SDR
References & Further Reading n n n n www. sdrforum. org Reed J. H. , Software Radio: A Modern Approach to Radio Engineering, Prentice Hall, 2002 Tuttlebee W. (Ed. ), Software Defined Radio: Origins, Drivers and International Perspectives, John Wiley & Sons, Ltd. , 2002 Brederlow R. , Weber W. , Sauerer J. , Donnay S. , Wambacq P. , Vertregt M. , A Mixed-Signal Design Roadmap, IEEE Design & Test of Computers, November-December 2001.  Software Communications Architecture Specification, MSRC-5000 SCA V 2. 2, November 17, 2001 Tuttlebee. W. (Ed. ), Software Defined. Radio: Enabling. Technologies, John Wiley& Sons, Ltd. , 2002. Dillinger. M. , Madani. K. , Alonistioti. N. (Editors), Software Defined. Radio: Architectures, Systemsand Functions, John Wiley& Sons, Ltd. , 2003. Mitola. J. , Software Radio Architecture: Object-Oriented. Approachesto Wireless. Systems. Engineering. John Wiley& Sons, Ltd. , 2000.
Quiz Define Software Radio. n What are the advantages of Software Radio technology? n What are the disadvantages of Software Radio technology? n