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Tuesday, December 14, 2010

Cognitive Radio – Communication Policy Challenges:

The Vision…………..
Just imagine if your cellular telephone, personal digital assistant (PDA), laptop, automobile, and TV were as smart as “Radar”. They would know your daily routines as well as you do. They would have things ready for you as soon as you ask, almost in anticipation of your need. They would help you find people, things, and opportunities; translate languages; and complete tasks on time. Similarly, if a radio were smart, it could learn services available in locally accessible wireless computer networks, and could interact with those networks in their preferred protocols, so you would have no confusion in finding the right wireless network for a video download or a printout. Additionally, it could use the frequencies and choose waveforms that minimize and avoid interference with existing radio communication systems.

A cognitive radio is the convergence of the many pagers, PDAs, cell phones, and many other single-purpose gadgets we use today. They will come together in the future to surprise us with services previously available to only a small select group of people, all made easier by wireless connectivity and the Internet.

New technologies impact the worlds of commerce and policy. This is especially true of disruptive technologies that significantly alter either the realities or perceptions within these worlds. Cognitive radio technology has the potential of affecting the marketplace for radio devices and services as well as changing the means by which wireless communications policy is developed and implemented. One of the key parameters that must be addressed to enter the radio market is access to radio spectrum. Once access is obtained, the capacity to manage interference becomes a key attribute in order to increase the number of users. Throughput is critical in order to maximize benefit (for the device) or maximize revenue (for the service). Radio frequency (RF) spectrum access and interference management are thus the primary roles of spectrum management. Cognitive radio technology has the potential of being a disruptive force within spectrum management.

The capacity to sense, learn, and adapt to the radio environment provides new opportunities for spectrum users. However, the same sensing and adaptation also creates challenges for policy-makers. The primary concern is with the potential to have nondeterministic behaviors. Nondeterministic behaviors can be created by a variety of conditions:
 The allowance of self-learning mechanisms will create a condition in which the response to a set of inputs will be changing and thus unknown.
 The allowance of software changes will create conditions either from errors within the software or from rogue software, which can cause the device to not conform to the transmission rules.
 The allowance of frequency and waveform agility will create conditions in which devices that conform to transmission rules may cause interference due to mismatch between out-of-band receivers and the in-band transmitter waveforms.

In addition to nondeterministic behaviors, another primary concern is the impact of horizontal versus vertical service structure. Vertically integrated services, such as cellular telephony, clearly delineate responsibility for spectrum management to the service provider. The service provider has the sole responsibility for problems, interference, and all other technical and service issues. However or horizontally integrated service, which includes device-centric systems that may be the initial focus for cognitive radio technology, there isn’t a single point of responsibility for interference and other problems. One example has been the issue with secondary spectrum markets. The formal responsibility of a device creating interference is the primary licensee. The rules had to be modified to allow that responsibility to follow the usage to the secondary licensee when appropriate. The extrapolation of this approach is problematic when applied to cognitive radios, as each device is, in essence, a licensee. This is a serious problem for the policy-makers that can be addressed by rules, technology, or a combination of both.

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