Security levels in wireless communication channels, grouped from most secure to least secure, can be broadly defined as:
The success of modern military forces depends a great deal on the effective use of sophisticated radio communication and navigation systems. Historically, the enemy has employed electronic countermeasures (ECM) to detect the presence of these radio signals and either disrupt them or exploit them. Radio systems can be disrupted by jamming or by locating and destroying them. On the other hand, exploitation involves using the transmissions for intelligence and counter-intelligence purposes. Prior to the development of high quality data security and transmission security techniques, it was possible to gather intelligence from the received signals by demodulating and decoding (deciphering) them. For simple systems it is also possible to "spoof" (or mimic) them to provide false information (counter-intelligence). Radio transmissions can also be exploited, even when they employ high quality security techniques, by simple radio direction finding (RDF) or position monitoring. A scenario of these basic ECM techniques is shown in the following figure.
There are some alternate terminologies used to describe ECCM concepts that need to be discussed. The first is Low Probability of Detection (LPD). LPD requirements are concerned with preventing the enemy from detecting a radio transmission. LPD applies to those techniques which minimize power spectral density and hence detection - the key element of ECCM. The second is Low Probability of Exploitation (LPE). LPE is concerned with preventing the exploitation of the signal by decoding, spoofing, or position monitoring. LPE design would deny the enemy knowledge of the system, its modulation characteristics, its use, and its users. The third term is Low Probability of Intercept (LPI) which encompasses both LPD and LPE. LPI is a generic term from which we derive the term anti-intercept. Most discussions on ECCM can be given in terms of AJ and LPD.
The top level of a wireless information network is shown in Figure 1. The public network (Internet and Phone) and the private network such as the one modeled as a university are usually not secure. The private networks modeled as an industry, a wireless service provider, and a private LAN are usually secure. Figure 1. also illustrates security firewalls for the secure private networks.
The present technology that implements the wireless channels (shown in red) is not secure except for some data encryption, authentication, and spread-spectrum implementations that provide limited protection to elementary attempts at jamming, spoofing, and interception.
Channel security characteristics for a secure public communication system are grouped into the categories shown in the following table:
Elements of Secure Public Communications | ||
Detection is usually used for determining activity and patterns of use and is the first step in employing additional ECM techniques.
Location ECM is used to locate and track wireless transmitters in the network. Programs now exist where a cell phone user can be located down to the cell site and antenna sector level.
Denial of Service is the single-most common ECM that will be used in the public system. There are numerous methods besides brute-force jamming that can be used in service denial which makes this the most promising area of ECCM research.
Counterfeiting is used to obtain service by non-legal means. Standards emphasize protection against counterfeiting but it cannot be eliminated.
Decoding of digital voice and data is probably going to be the least important area of research since practical data encryption methods are well advanced.
Spoofing is the second most promising area of ECCM research because of all of the protocols used in initiating and validating a wireless link.
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