Software defined radio (SDR) has become a hot topic in the industry and is seen as a solution for many of the development problems for new radio platforms. It is generally perceived that SDR is the answer to the need for flexibility, upgradability, and the problems of implementing multiple radio standards alternatively and even running several services in parallel. An SDR-based platform can also reduce the high development costs of a full new ASIC-based solution.
But what is really meant by software defined radio? It is not only a system on a chip (SoC) radio receiver with "software inside." This approach is already state of the art. Modern radio receiver chipsets already count on embedded cores, where software implements many parts of the functionality. Even radio receivers for the old fashioned FM radio are implemented digitally as software solutions on embedded cores or standard DSPs. The software may be embedded in a chip or chipset without being visible to the outside world.
The advantages of such solutions are clear. A software-based solution can be modified in the very late stages of the development process, and to some extent be reused across SDR platform generations. Certain standard software functions and libraries on the market are licensable as intellectual property (IP) or core developer kits (CDK). Audio and video decoder software libraries are a typical example of such IP. Another advantage of these software solutions is the possibility for updates or bug fixes after delivery of a development, when a problem encountered in the field requires countermeasures.
Software defined radio is more than just an implementation in a software solution. It means the hardware platform obtains its functionality only when the software and the hardware development is independent, but it is influenced by the software development. The concept relies on the split between a suitable hardware platform and a suitable set of functionalities to be implemented on the platform.
There are two principal scenarios:
First, the hardware platform to be used is a standard platform, which can be ordered as a standard component. Examples for such hardware platforms are the C64+ DSP-family from Texas Instruments, the Blackfin DSP-family from Analog Devices or Infineonís SDR20, among others.
This is different to the second case of proprietary programmable platforms with DSP IPs, like ARM, Tensilica, MIPS or others inside. All silicon vendors have such devices in their portfolio for existing or future radio applications. The main difference is that the knowledge of how to use the device most effectively requires a very close cooperation with the silicon vendor. This is a different business relationship to the silicon vendor compared to ordering standard components. The devices are often very heterogeneously built based on one or more embedded cores. The advantage is the possibility to optimize the platform for an application or family of applications. Normally the intended feature-set or applications are known upfront and the hardware has to be targeted for the purpose. Therefore, such SDR platforms are in principle a multi-standard terminal, which can be used for different radio applications alternatively or even in parallel.
Although the topic is broad in nature, I do appreciate the effort to highlight some of the implementation architectures. Great way to enlighten us!
However, was the goal to constraint the discussion to the physical layer implementation?
Lifewingmate, brought a good comment regarding the application layers were SDR shines and provides features that a strictly fixed or programmable hardware solution cannot.
I wonder if software-defined radio can sync with social media and become interactive with the use of applications and smartphones. Is XM radio a form of this popular technology? Would Pandora, Grooveshark, and other songlist/station builder software pieces empowering the continued design of smart software-defined radios? This is an interesting article and I'm interested to hear more about the salabilitly challenges which drive the demand.
Nice to our colleagues in Iraq joining in the discussion.
I think C Davis identified the biggest challenges for SDR in consumer products: cost, power and size. SDR makes much more sense for military applications, where there are so many different waveforms to support and legacy radios to emulate.
Dear Editor... I need to thank the authors of this paper.. I faced the problem of SW defined Radio at the begining of my Phd at 1981. Since that time many scientists facing such challenges, due to many big problems in designing and implementations of the normal transceivers in any specified frequency band or specified applications. What really facing us now after such long period (more than 30 years!), what is really the main challenges for such direction of Radios?.. I think such aspect needs more discuissions.
Dr. Eng. Sattar B. Sadkhan
Chairman of IEEE IRAQ Section
University of Babylon - Computer Technology College
Itís a good technology for the military (and is deployed heavily). I looked at starting up a company to do this in 2003. For the commercial/consumer space, my estimates indicated that SDR always consumes more power and space (i.e. cost) for 3 and less radios. This is a killer for consumer type devices. With life spans of devices of 24 months or less, the additional flexibility doesnít have much perceived value. If we come up with a use case where we have 5+ radios that can be time sliced, it would likely make sense.
I would say Spectrum Sensing Reallocation Strategy would by far be the most powerful of the use cases. Could lead to a stage where spectrum auctions would need to include usage stats rather than selling chunks.
Fairly high level.. SDR as a concept is great but when trying to meet timing requirements on several of the new technologies, it requires a lot of tweaking and in some cases might just not apply.. Discussion on implementation details of a design might help the audience more
Software defined radio continues to be a hot topic with its best applications still up for debate. Sound off here in the comments on what you think the future is for SDR, or if you have questions for the authors.