SDR: Today and Future

I also got an opportunity to attend the SDR briefing in LTE World Summit. There were many interesting presentations including one titled "SDR in Mobile Devices" by Thierry Dubois, SDR Market Analyst, IMEC, Belgium. Infact last year I blogged about SDR from Imec presentation as well. The following is an extract from Thierry's presentation:

The key benefits of SDR are as follows:

• Reducing the Bill Of Materials (BOM)
• Lower development costs
• Facilitate better reuse of intellectual property (IPR)
• Possibility to upgrade products already in the field
• Enabler of the Cognitive Radio vision

There are three main areas where SDR's are required but some problems exist as can be seen from the diagram above.

• Flexibility is the key for baseband. Some of the common signal processing blocks may not be reusable. This means that though some protocols can easily be defined for a particular baseband, others may not be possible for that baseband. Good progress is still being made though on this front.
• Reconfigurable RF is some way away, further down the road.
• The biggest challenge is the antenna interface for which no proper solution exists. Some solutions being worked on right now include MEMS based solution, Carbon nanotubes, Special ceramic materials, etc.

The next step after SDR is cognitive radio (CR). The main advantage for using CR would be because spectrum is over-allocated but under-utilised. There are lots of white spaces in the spectrum that could be utilised by devices intelligently of their own.

Cognitive Radios are defines as: A radio that can autonomously change its parameters based on interaction with, and possibly learning of, the environment in which it operates. Through appropriate radio resource management, such a cognitive radio should make flexible and efficient use of network/spectrum resources.

CR would consist of Intelligent Sensing hardware and Intelligent Sensing Algorithms. There are two types of CR being considered:

• Opportunistic Radio: A radio that co-exists with other systems using the same spectrum. E.g., White Space Devices
• Smart Reconfigurable Radio Systems: A radio that makes flexible and efficient use of network/spectrum resources across heterogeneous environments. Seamlessly roaming possible on different networks, countries, frequencies, etc. It requires true paradigm shift i.e., spectrum liberalization

An Introductory paper on SDR is available on Bitwave Semiconuctor website.