Bruce A. Fette

Radio frequency watermarking for OFDM wireless networks

In this work, we apply watermarking to the physical layer of the wireless baseband modulation waveform, with the motivation to improve flexibility and efficiency of authentication processes in a secure wireless network. We present two baseband watermarking methods, called constellation dithering (CD) and baud dithering (BD), applied to orthogonal frequency division multiplexing (OFDM). We provide the watermark detection and capacity performance attributes in an additive white Gaussian noise (AWGN) channel. Both watermarking techniques allow interoperability with uninformed systems (such as receivers in the 802.11 WLAN commercial standard). Results indicate that, while the BD method provides higher detection robustness and capacity, the CD method exhibits more performance flexibility and is easily modified to the desired user characteristics.

History and Background of Cognitive Radio Technology

This chapter discusses the history and background of cognitive radio technology. The sophistication possible in a Software Defined Radio (SDR) has now reached the level where each radio can conceivably perform beneficial tasks that help the user, help the network, and help minimize spectral congestion. Some radios are able to demonstrate one or more of these capabilities in limited ways. SDR is a radio in which the properties of carrier frequency, signal bandwidth, modulation, and network access are defined by software. Modern SDR also implements any necessary cryptography, forward error correction coding, and source coding of voice, video, or data in software as well. Todays SDR, in contrast, is a general-purpose device in which the same radio tuner and processors are used to implement many waveforms at many frequencies. The advantage of this approach is that the equipment is more versatile and cost effective.

The Software Defined Radio as a Platform for Cognitive Radio

Publisher Summary This chapter explores both the hardware and software domains of software-defined radio (SDR). Although a software-defined radio is not a necessary building block of a cognitive radio (CR), the use of SDR in CR can provide significant capabilities to the final system. An SDR implementation is a system decision, in which the selection of both the underlying hardware composition and the software architecture are critical design aspects. The selection of hardware composition for an SDR implementation requires an evaluation of a variety of aspects, from the hardwares ability to support the required signals to other performance aspects, such as power consumption and silicon area. Traditional approaches can be used to estimate the needs at the RF and data acquisition levels. At the processing stage, it is possible to create an estimate of a processing platforms ability to be able to support a particular set of signal-processing functions. With such an analysis, it is possible to establish the appropriate mix of general-purpose processors (GPPs), digital signal processors (DSPs), field-programmable gate arrays (FPGAs), and custom computing machines (CCMs) for a particular set of signal-processing needs.

Cognitive Techniques: Position Awareness

Publisher Summary This chapter covers number of ways to determine where a system is located. An inertial navigation system can be used to integrate a current position relative to a known starting point, but this approach is fraught with unreliability and excessive expense. A better alternative is a GPS receiver. This inexpensive subsystem provides 3-D position and current time. The system is based on a constellation of satellites and it has the capability for two resolutions, precise positioning system and standard positioning system. The chapter focuses on the value of geolocation knowledge to enable spatially aware networking functions. It briefly reviews how networking provide a coarse degree of localization and explores how geolocation is extended to become boundary analysis. One of the key interfaces to a geolocation engine is a boundary decision. This approach may be used for a variety of other regions of interest decisions as well. The chapter also provides examples of geolocation in the context of cellular emergency location and reviewes the many interfaces to other supporting subsystems a CR will need to build well-integrated, systems-level functionality.

Introducing Adaptive, Aware, and Cognitive Radios

In the late 1990s, nearly all telecommunications radios were built using digital signal processor (DSP) processors to implement modulation and signal processing functions, and a General Purpose Processor (GPP) to implement operator interface, network signaling, and system overhead functions. This architecture is attractive to a manufacturer because the same basic electronics can be used over and over for each new radio design, thereby reducing engineering development, enabling volume purchasing, and optimizing production of a common platform, while retaining the flexibility for sophisticated waveforms and protocols. A few manufacturers called their radios “Software Defined Radios” (SDRs), recognizing the power and market attractiveness of the customer community being able to add additional functionality that is highly tuned to market specific applications. In the early 2000s, a few of these vendors made application layer software functionality available for additional value added functions to aid the user. Users could add music, games, or other applications, as long as the radio waveform functions remained untampered. Similarly, in the late 2000s, many radios will make the software functionality available for various classes of adaptivity and significantly extend user support functionality. This will initiate the generation of “Cognitive Radios”. Thus, with minimal additional hardware, additional software features will enable users, network operators, spectrum owners, and regulators to accomplish much more than with the fixed application radios of an earlier generation. To understand this important design trend, we must first understand the background, history, and terminology.

The Really Hard Problems

This chapter recognizes several classes of radios. The radio designed and built for defense applications. When used in peacekeeping missions, such radios will be expected to comply with the regulatory requirements of the regions where they are used. It requires to have details of the radio networks of other allies and coalition partners, including waveforms, protocols, frequencies, and what conditions should be communicated with the partners. These radios are the gateway for many local users to reach many global networks and have access to numerous computer servers and database servers through those gateways. Most such radios are designed to have considerable built-in intelligence; in addition, the access to intelligent pull and push services through their networks will be very significant. The information available to such a radio is limited by the bandwidth of the most restrictive wireless links providing the access, by the battery power available, and by the total time the mission must be operative on that battery power.

Chapter 1 – History and Background of Cognitive Radio Technology

Publisher Summary This chapter presents an overview of history and background leading to cognitive radio. It provides some of the major contributions that have led up to todays cognitive radio developments. A cognitive radio is the convergence of the many pagers, personal digital assistant (PDAs), cell phones, and many other single-purpose gadgets use today. The sophistication possible in a software-defined radio (SDR) has now reached the level where each radio can conceivably perform beneficial tasks that help the user, help the network, and help minimize spectral congestion. Radios are already demonstrating one or more of these capabilities in limited ways. A simple example is the adaptive digital European cordless telephone (DECT) wireless phone that finds and uses a frequency within its allowed plan with the least noise and interference on that channel and time slot. Of these capabilities, conservation of spectrum is already a national priority in international regulatory planning. This chapter introduces the technologies and regulatory considerations to support three major applications that raise an SDRs capabilities and make it a cognitive radio: spectrum management and optimizations, interface with a wide variety of networks and optimization of network resources, and interface with human and providing electromagnetic resources to aid the human in his or her activities.

Chapter 16 – The Really Hard Problems

Publisher Summary The ability to improve spectral efficiency, enhance network efficiency, and serve the telecommunication user—the purview of cognitive radio (CR)—is an application that adds significant value to the telecommunication market. CR is a radio that is sufficiently intelligent to aid spectrum efficiency, aid the radio networks and network infrastructures, and aid the user. This chapter presents several classes of radios. To begin with, there is the radio designed and built for defense applications. When used in peacekeeping missions, such radios are expected to comply with the regulatory requirements of the regions where they are used. They will need to have details of the radio networks of other allies and coalition partners, including waveforms, protocols, frequencies, and what conditions should be communicated with partners. The second class of radio involves the cellular telephone subscriber unit, the corresponding base station, and its corresponding infrastructure. The third class of radio is those embedded into computing devices. This includes laptop computers, PDAs, and similar devices, for which the primary access is a wireless personal area network. The chapter also predict a fourth class of radio: automobiles that will soon have an add-on business of transmitting and receiving useful services to the driver and passengers by using wireless regional area network (WRAN) services.