The Pros And Cons Of Cognitive Radio Technology

According to survey of Federal Communications Commission (FCC) in 2002, it has been found that spectrum access is more significant problem than physical scarcity of spectrum. With many technological advances in the field of wireless communication and 3G, 3.5G, 3.75G and 4G technology already being employed Multimedia Broadcast and Multicast Services (MBMS) demand has tremendously increased and with the standardization of MBMS it has gained significant interest in the market. Multimedia content requires more bandwidth, storage capacity and few applications pose tight delay constraints, so the need to optimize the utilization of spectrum is felt all the more.

The available radio spectrum is limited and it is getting crowded day by day as there is increase in the number of wireless devices and applications Cognitive radio technology proposed tempting solution for spectral crowding problem by introducing the opportunistic usage of frequency bands. Which are not heavily occupied by licensed users since they cannot be utilizing by the users other than the licensed owner at moment. Orthogonal Frequency Division Multiplexing (OFDM) is one of the widely used technologies in wireless communication systems which have the potential of fulfilling the requirements of cognitive radios inherently or with minor changes.

1.2 Basic of Cognitive Radio (CR)

Cognitive radio (CR) concept was first proposed by Joseph Mitola III in a seminar at KTH (the Royal Institute of Technology in Stockholm) in 1998 and published in an article by Mitola and Gerald cognitive radio is an emerging technology that can be programmed and configuring dynamically. Its transceiver is designing for the use of best wireless channels in its vicinity. Cognitive radio automat...

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...rum sensing which is analyze the situations of several factors in the external and internal radio environment (such as radio frequency spectrum used by neighboring devices, users behavior and network state) and finding the optimal communication protocol and changeable frequency or channel accordingly. It is also known as channel estimation.

1.5 (c) Spectrum Decision Making

Spectrum Decision Making calls for reconfiguration for the channel and protocol required for constantly adapting to mobile changing environments and adjustment of output power or even alteration of transmission parameters (such as modulation formats (e.g. low to high order QAM), variable symbol rates, different channel coding schemes) and characteristics by the Cognitive radio devices. CR should be able to use multiple antennas for interference knolling, capacity increase or range extension.