The invention generally relates to devices in a cognitive radio network, and more particularly, to a method and device for dynamically reconfiguring a regulation-compliance mode based on use of the device's incumbent protection mechanism capabilities.
In an effort to increase spectrum usage efficiency, wireless spectrum regulation has been increasingly changed towards allowing secondary users to dynamically access channels not being used by primary users. However, in allowing secondary users access to the wireless spectrum, regulatory bodies like the Federal Communications Commission (FCC) in US and Ofcom in UK, define a set of mechanisms to protect primary users from interference caused by the secondary users. Secondary users are required to employ the protection mechanisms, known as primary protection mechanisms, in order to operate in the regulated wireless spectrum of the primary users.
Depending on the primary protection mechanisms employed, a secondary user is classified into one of several regulation-compliance modes. Each primary protection mechanism or regulation-compliance mode has its own advantages and limitations when it comes to operation. For example, the cost (implementation and operating cost) and the degree of freedom to operate (in terms of network formation, channel selection, and transmission power limit) may vary. A device which employs a more complete set (or more tiers) of protection mechanisms normally enjoys a higher degree of freedom to initiate a network and select a channel and set a transmission power limit, at the expense of higher implementation cost.
The regulatory bodies classify the secondary users into several regulation-compliance modes depending on the primary protection mechanism employed. For example, the FCC defines three regulation-compliance modes for unlicensed personal/portable devices (secondary Television Band Devices, TVBD) to operate in the TV band, where TV stations and wireless microphones are incumbents (primary users). These 3 regulation-compliance modes are Mode II, Mode I, and sensing-only mode. In addition, the FCC also defines a fourth regulation-compliance mode device for high-power unlicensed TVBDs (as opposed to personal/portable TVBDs), namely a fixed device.
A device operating in Mode II is required to have the capability to determine its location with +/−50 m accuracy and access a TV band database in order to determine channel availability. Current rules also require Mode II devices to have an additional spectrum sensing capability. A Mode II device is allowed to initiate a network and set its transmit power limit to 100 mW. In contrast, a Mode I device is not required to have the geolocation capability or to access the TV band database, but is required to have sensing capability. However, Mode I devices cannot initiate a network and are only allowed to operate as a dependent device, enabled by a Mode II device (or a fixed device). A sensing-only device employs the sensing capability and is not required to have the geolocation capability or access to the TV band database. The sensing-only device can initiate a network and determine channel availability independently. However, the transmission power of the sensing-only device is limited to 50 mW. As another example, the spectrum regulator in the UK (Ofcom) allows two regulation-compliance mode devices: geolocation-only or sensing-only.
Each primary protection mechanism and hence, regulation-compliance mode, has advantages and limitations when it comes to operation. The geolocation-database approach (Mode II) relies on real-time geolocation and timely access to the Internet, which could be lost or not available at certain times and in certain locations, or could be very costly if a device relocates often. According to current FCC rules, if the location changes, a Mode II device needs to query the TV band database again. For the sensing approach, a quiet period during which all transmissions are suspended is needed, which costs spectrum usage efficiency. Sensing is also subject to false alarms by incorrectly treating noise as a primary signal. The sensing-only device is only allowed to transmit at a lower power limit than those supporting the geolocation database approaches.
Thus, as pointed out above, secondary devices are limited by regulatory compliance requirements. Restricting a secondary device to one regulation-compliance mode limits its operational flexibility and/or increases its operating cost, such as power consumption.
In accordance with one embodiment of the present invention, a method for dynamically reconfiguring the regulation-compliance mode of a secondary device based on the use of a set of primary protection mechanism is proposed. One of the advantages of the proposed method is that the operating cost of the secondary device may be lowered, and its degree of freedom to select channel and transmission power may be increased. As a result, a TVBD may have longer battery life, more channels to choose from, and/or higher link quality.
According to an exemplary embodiment of the invention, the disclosed features allow a secondary device:
to identify the regulation-compliance mode of itself and other secondary devices and act accordingly to establish communication;
to dynamically reconfigure its regulation-compliance mode to best suit the needs of network-operation. For example, a sensing and geolocation database combo device (e.g., Mode II TVBD) may turn off geolocation and TV band databases access to rely on sensing-only in order to improve its portability/mobility.
to enable a dependent device through an enabling signal.
In one example embodiment of the invention, a method is provided for dynamically reconfiguring a regulation-compliance mode of a device that is part of a wireless network and is operating under a network-operation mode in a spectrum band with primary users. The method includes periodically determining at least one of: a primary protection capability of the device, availability of an enabling signal to the device, and a frequency of location change of the device; and based on the results of such determinations, operating and configuring transmission parameters of the device according to one of a plurality of regulation-compliance modes that are supported by the device based on its network-operation mode.
In another example embodiment of the invention, a device, being part of a wireless network, is provided for operating under a network-operation mode in a spectrum band with primary users. The wireless device includes: a signal transceiver for processing, transmitting and receiving wireless signals from secondary devices; a primary signal sensing module for detecting a primary signal; and a spectrum manager for selecting or deselecting an operating frequency channel. The wireless device may further include a network interface for accessing a TV-band database, and determining its geolocation.
The subject matter that is regarded as the invention is particularly pointed out and distinctly claimed in the claims at the conclusion of the specification. The foregoing and other features and advantages of the invention will be apparent from the following detailed description taken in conjunction with the accompanying drawings.
It is important to note that the embodiments disclosed are only examples of the many advantageous uses of the innovative teachings herein. In general, statements made in the specification of the present application do not necessarily limit any of the various claimed inventions. Moreover, some statements may apply to some inventive features but not to others. In general, unless otherwise indicated, singular elements may be in plural and vice versa with no loss of generality. In the drawings, like numerals refer to like parts through several views.
As shown in
For a secondary client device 111, the spectrum availability is normally determined by spectrum sensing of primary devices 121, as well as the signalling received from its associated secondary master device 101.
The components, including the device manager 206 may be implemented as a hardware component (hardware circuit) which includes, for example, a field programmable gate array (FPGA), application specific integrated circuit (ASIC), gate array, combination of logical gates, signal processing circuit, analog circuit and the like. The components may include a software component as a part (fragment) for realizing the processing described above as software, and is not a concept which limits the language, the development environment and the like for realizing the software. The software component includes, for example, a task, process, thread, driver, firmware, database, table, function, procedure, subroutine, certain part of program code, data structure, array, variable, parameter and the like. Such a software component is realized on one or multiple memories (one or multiple special processors (for example, a specific CPU (Central Processing Unit), a DSP (Digital Signal Processor) and the like). Each of the embodiments described above does not limit the method of realizing each of the processing sections described above.
As illustrated in
In one example embodiment, at least one device transmits beacons periodically with the medium access control (MAC) superframe timing structure 400 as illustrated in
The device type is characterized by the selected network-operation mode and a regulation-compliance mode, as well as a security mode (optional). The network-operation mode indicates the network topology formation and the role of the device in the network. The network-operation mode can be a master, slave, or peer device.
The regulation-compliance mode is defined by regulation. In the FCC example discussed above, the regulation-compliance mode can be Mode II, Mode I, or sensing-only mode. In another example (Ofcom), the regulation-compliance mode can be geolocation-only or sensing-only.
In an example embodiment, if a device is a beaconing device, the device type should be incorporated in a beacon frame. A master device and a peer device are beaconing devices. A slave device can be a beaconing device depending on its capability. A beacon is transmitted periodically in the beacon period (BP), having a beacon frame payload format as illustrated in Table 1.
The information field coding of the device type is illustrated in Table 2 according to an example embodiment.
A device operating in regulation-compliance mode (Mode II) can enable a dependent device which by itself cannot determine channel availability. To do that, the enabling device (Mode II device) needs to indicate a regulation-compliance mode and transmission power limit of the available channels for the dependent device to operate.
The enabling signal is defined as follows:
The transmission power limit is defined per channel. The inband transmission power limit is the transmission power limit of the current operating channel. The permissible outband channel is an available channel, other than the current operating channels. Permissible outband channels can be used for a backup channel. If the current operating channel becomes unavailable, one permissible outband channel can be selected as the new operating channel. The information elements of the inband transmission power limit and the permissible outband channel are illustrated in Table 3 and Table 4, respectively.
The enabling signal is transmitted periodically by the enabling device in its beacon. Once the enabling signal is received, a device can operate as a dependent device with respect to the enabling device. The dependent device needs to indicate its regulation-compliance mode and configure its own transmission parameter (the channel set and transmission limit) as indicated by the enabling device.
A master device may operate in either Mode II (or geolocation-only in the UK) or sensing-only mode. A slave device may operate in either Mode I or sensing-only mode. A peer device may operate in Mode II, Mode I, or sensing-only mode. The relationship between regulation-compliance mode and network-operation mode is illustrated in Table 5.
Note that it is possible that some slave devices may have the capabilities to operate in Mode II.
The regulation-compliance mode can be changed from one to another based on the following inputs:
The flowcharts of (re)configuration of the regulation-compliance mode are illustrated in
The invention is applicable to, for example, IEEE 802.11, IEEE 802.15 and ECMA TC48-TG1, as well as other emerging cognitive radio standards.
The foregoing detailed description has set forth a few of the many forms that the invention can take. It is intended that the foregoing detailed description be understood as an illustration of selected forms that the invention can take and not as a limitation to the definition of the invention. It is only the claims, including all equivalents that are intended to define the scope of this invention.
Most preferably, the principles of the invention are implemented as any combination of hardware, firmware and software. Moreover, the software is preferably implemented as an application program tangibly embodied on a program storage unit or computer readable storage medium consisting of parts, or of certain devices and/or a combination of devices. Computer readable storage media comprise all computer-readable media except for a transitory, propagating signal. The application program may be uploaded to, and executed by, a machine comprising any suitable architecture. Preferably, the machine is implemented on a computer platform having hardware such as one or more central processing units (“CPUs”), a memory, and input/output interfaces. The computer platform may also include an operating system and microinstruction code. The various processes and functions described herein may be either part of the microinstruction code or part of the application program, or any combination thereof, which may be executed by a CPU, whether or not such computer or processor is explicitly shown. In addition, various other peripheral units may be connected to the computer platform such as an additional data storage unit and a printing unit.
This application claims the benefit of U.S. Provisional Application No. 61/231,388 filed on Aug. 5, 2009.
Filing Document | Filing Date | Country | Kind | 371c Date |
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PCT/IB10/53184 | 7/12/2010 | WO | 00 | 2/2/2012 |
Number | Date | Country | |
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61231388 | Aug 2009 | US |