Table 2 Comparison of SDR, programmable MAC, and CR paradigms

Raison d’être

Software defined ability to adapt/program PHY and MAC layer characteristics.

Using ‘cognition’ to drive the capability of adapting (typically providing by SDRs) to optimize the network performance.

Supporting custom creation of MAC protocols, rather than hard-wired MAC, through appropriate vendor-independent abstractions.

Supporting custom data plane processing to facilitate customized processing of the packets in the data line.

Applications

Reconfigurability, building block of cognitive radio, interoperability, more degrees of freedom.

Dynamic spectrum access (DSA); interoperability and improved handovers; link optimization (modulation, power, topology, etc.); better resource utilization; increased capacity, reliability, and security; technology neutral coexistence.

Defines primitives for composing custom MAC protocol logic which can program the whole radio protocol stack independently of the platform (analogously to Java Applet).

Useful for developing software-defined routers with customized data planes that allows custom protocol operations and/or any arbitrary payload processing at the network-layer.

Strengths

Lower life cycle cost, increased interoperability with multiple waveforms, field upgradable, demonstrates hardware flexibility.

They inherit the strengths of SDR (being SDR-based typically). They can learn about the environment and self-optimize by modifying radio parameters accordingly to ensure certain QoS. Hardware and policy flexibility.

Provides some capabilities of a full SDR on commodity WLAN hardware allowing support for arbitrary MAC protocols. This results in a cheaper solution that is also simpler. The main strength of this approach is programmability.

Flexibility in programming arbitrary processing in the forwarding plane. This can allow routers to diversifying beyond a forwarding only regime into the territory ofmiddleboxes to define customized data plane processing of packets.

Weaknesses

Basic hardware of SDR is typically more expensive that single-mode hardware radio.

Numerous technical hurdles must still be overcome for CR to be ready for implementation in a real world scenario. A commercial fully functional CRN is yet to emerge.

More work needs to be done to support more sophisticated abstractions widely on commodity devices.

Not deployed widely. May not match the processing ability of fixed routers with predefined data plane processing.