Patent Application
20080194215
The present invention relates to wireless communication location devices and, more particularly, to transmitting data reliably over long distances using low power.
The use of portable electronic devices and mobile communication devices providing location based information has increased dramatically in recent years. Moreover, emergency communication systems are being upgraded on a regular basis to provide improved features, such as faster response times and better accuracy in location determination. A mobile communication device includes a transmitter to send data, such as location information, to a receiving emergency communication system. The receiving system can identify a location of the mobile device from the data and report the location to emergency dispatch teams. The mobile communication device can include a location unit, such as GPS for identifying a location of the device, and a transmitter for sending the location information.
A mobile communication device can be a radio or a cell phone. A radio, which provides two-way dispatch communication, is generally larger in size than a cell phone. The transmitter in a radio generally includes a power amplifier with a high power rating, whereas a transmitter in a cell phone generally includes a power amplifier with a low power rating. The radio can support larger heat sinks that are more capable of dissipating heat from the power amplifier than a small cell phone. Consequently, a high power transmitter in a radio is capable of sending data over longer distances than a low power transmitter of a cell phone.
Low power devices such as cell phones have a transmitter with limited heat sinking that are usually designed to operate under 1 W of average power. In certain cases, the low power transmitter can be requested to transmit data, such as location data, at a higher power or at a higher transmit rate during an emergency situation. This allows the transmitter to increase the range of the mobile communication device in an emergency situation for sending location information. However, requiring the transmitter to operate above a normal specified rating over prolonged periods can result in an overheating of the power amplifier which results in degraded transmit performance. If the power amplifier is operating at a higher power than it's nominal specification, excess heat will be generated and eventually reduce the efficiency of the transmitter. A need therefore exists for allowing a low power mobile communication device to operate at a higher than normal specification for sending location data, or any other information, in an emergency situation.
One embodiment is a method for reliably sending data from a transmitter of a wireless communication device. The method can include determining if the transmitter is sending data at an increased power level, evaluating a transmission time for sending the data, evaluating a temperature margin for the transmitter operating at the increased power level in view of the transmission time, and controlling a transmitting of the data at the increased power level based on the temperature margin to protect the transmitter from excessive heat build-up. In such regard, the transmitter will be protected from excessive heat when it is enabled to operate at a much higher power than its intended design. In one arrangement, a pulse compressed signal can be transmitted at a transmitter peak power to increase a transmit range of the wireless communication device in an emergency. Location specific information can be included in the pulse compressed signal for identifying a location of the wireless communication device
The step of evaluating a temperature margin can include determining a data size of the data, determining a data rate of the wireless communication device, and calculating the transmission time from the data size and the data rate. The step of controlling includes increasing or decreasing a continuous outflow of the data during the transmitting based on the data size. The step of evaluating a temperature margin can also include checking a present temperature of the transmitter, determining a rise time of the transmitter to reach a threshold temperature in view of the present temperature, and comparing the transmission time to the rise time to identify a temperature margin.
The step of determining a rise time can include performing a look-up search in a table that charts a temperature of the transmitter versus time with respect to the data rate. A rise time is a time it can take for the transmitter operating at the increased power level to reach the threshold temperature at the data rate. The table can include a temperature profile of the transmitter at the increased power level for a plurality of data rates and transmission times. The data can be transmitted if the temperature margin is positive which occurs when the transmission time is less than the rise time. Alternatively, the data can be temporarily stored if the temperature margin is negative. The method can then include waiting for an operating temperature of the transmitter to fall to a low temperature at which the temperature margin is positive and results in a rise time that is greater than the transmission time before retransmitting the data.
Another embodiment is a wireless communication device comprising a processor, a transmitter operably coupled to the processor that transmits data, and a memory operably coupled to the processor. The memory stores operating instructions that, when executed by the processor, cause the processor to determine if the transmitter is sending data at an increased power level, determine a data size of the data, determine a data rate of the wireless communication device, calculate a transmission time from the data size and the data rate, evaluate a temperature margin for the transmitter operating at an increased power level in view of the transmission time, and control a transmitting of the data at the increased power level based on the data size in view of the temperature margin for protecting the transmitter from excessive heat build-up due to transmitting at the increased power level.
A temperature sensor is operably coupled to the processor that measures a temperature of the transmitter to allow the processor to control a transmitting of data depending on the data size. The processor can receive temperature readings from the temperature sensor, check a present temperature of the transmitter when ready to transmit the data, determine a rise time of the transmitter to reach a threshold temperature in view of the present temperature, and compare the transmission time to the rise time to produce the temperature margin. A look-up table is included that charts a temperature of the transmitter versus time, wherein the operating instructions cause the processor to perform a look-up search for a rise-time in the table. The table includes a temperature profile of the transmitter at the increased power level for a plurality of data rates and a plurality of transmission times.
A global positioning system (GPS) receiver, can be included that is operably coupled to the processor, can receive GPS signals from a plurality of orbiting satellites. The operating instructions further can cause the processor to determine the location of the wireless communication device based at least in part on the GPS signals, and transmit the location with the data. A display can be included that is operably coupled to processor that identifies when the transmitter is operating at the increased power level in an emergency situation.
Yet another embodiment is a wireless communication device tracking system comprising a processor, a transmitter operably coupled to the processor, a temperature sensor operably coupled to the processor that measures a temperature of the transmitter; a location unit coupled to the processor, and memory operably coupled to the processor and location unit. The memory stores operating instructions that, when executed by the processor, cause the processor to determine a location of a wireless communication device from the location unit; create a short message service (SMS) data that includes the location, determine a file size of the SMS data; determine a data rate of the wireless communication device, calculate a transmission time from the file size and the data rate, evaluate a temperature margin for the transmitter operating at an increased power level in view of the transmission time, and control a transmitting of the data by the transmitter at the increased power level based on the temperature margin for protecting the transmitter from excessive heat build-up due to transmitting at the increased power level.
In one arrangement the transmitter is a pulse compression system that transmits the SMS data as a continuous chirp signal at high power for transmitting the SMS data over a long range. The processor monitors the temperature of the transmitter from the temperature sensor in view of the file size, and decreases transmission when the temperature margin is negative and increases transmission when the temperature margin is positive. A look-up table charts a temperature of the transmitter versus rise time. The processor performs a look-up search for a rise-time in the table that corresponds to a file size and data rate. The processor subtracts the transmission time from the rise time to determine the temperature margin. The processor can transmit the SMS data if the temperature margin is positive, at which the transmission time is less than the rise time, or, temporarily store the SMS data if the temperature margin is negative, and wait for an operating temperature of the transmitter to fall to a low temperature at which the temperature margin is positive and results in a rise time that is greater than the transmission time before retransmitting the SMS data.
The features of the system, which are believed to be novel, are set forth with particularity in the appended claims. The embodiments herein, can be understood by reference to the following description, taken in conjunction with the accompanying drawings, in the several figures of which like reference numerals identify like elements, and in which:
While the specification concludes with claims defining the features of the embodiments of the invention that are regarded as novel, it is believed that the method, system, and other embodiments will be better understood from a consideration of the following description in conjunction with the drawing figures, in which like reference numerals are carried forward.
As required, detailed embodiments of the present method and system are disclosed herein. However, it is to be understood that the disclosed embodiments are merely exemplary, which can be embodied in various forms. Therefore, specific structural and functional details disclosed herein are not to be interpreted as limiting, but merely as a basis for the claims and as a representative basis for teaching one skilled in the art to variously employ the embodiments of the present invention in virtually any appropriately detailed structure. Further, the terms and phrases used herein are not intended to be limiting but rather to provide an understandable description of the embodiment herein.
The terms “a” or “an,” as used herein, are defined as one or more than one. The term “plurality,” as used herein, is defined as two or more than two. The term “another,” as used herein, is defined as at least a second or more. The terms “including” and/or “having,” as used herein, are defined as comprising (i.e., open language). The term “coupled,” as used herein, is defined as connected, although not necessarily directly, and not necessarily mechanically. The term “processing” can be defined as number of suitable processors, controllers, units, or the like that carry out a pre-programmed or programmed set of instructions.
Referring to
In dispatch mode, the mobile communication devices 102 and 103 can communicate over one or more channels within a frequency band of the RF link 121. For example, a radio frequency spectrum can be divided into a plurality of frequency bands such as UHF and VHF. As is known in the art, Very high frequency (VHF) is the radio frequency range from 30 MHz to 300 MHz. In contrast, Ultra high frequency (UHF) designates a range (band) of electromagnetic waves whose frequency is between 300 MHz and 3.0 GHz. UHF frequencies' propagation characteristics are ideal for short-distance terrestrial communication such as radio communication. Ultra high frequency (UHF) designates a frequency range between 300 MHz and 3.0 GHz UHF frequencies' propagation characteristics are ideal for short-distance terrestrial communication such as radio communication. As one example, the UHF band can support the Family Radio Service (FRS) which is an improved two-way system or Public Safety Radio Services for providing emergency communication.
In another arrangement, the mobile communication devices 102 and 103 can communicate over a wireless local area network connection (WLAN) (not shown). In a typical WLAN implementation, the physical layer can use a variety of technologies such as 802.11b or 802.11 g Wireless Local Area Network (WLAN) technologies. The physical layer may use infrared, frequency hopping spread spectrum in the 2.4 GHz Band, or direct sequence spread spectrum in the 2.4 GHz Band, or any other suitable communication technology. The mobile devices 102 and 103 can communicate with one another using low power communications, such as Bluetooth or ZigBee
Briefly, the mobile communication device 102 can operate in a normal mode during normal use or in a pulse compressed mode during emergency situations. In normal mode, the mobile device 102 is capable of transmitting communication signals within a first range, or distance. For example, in normal mode, the radio can communicate with the base station 110 if the mobile device 102 is within a cell site area of the base station. If the mobile device 102 is outside the cell site area, and there are no other base stations, or other receiving communication devices, the mobile device 102 will not be able to communicate with other devices systems in normal mode. In an emergency situation where a user of the cell phone is outside of a coverage area, the mobile device 102 can switch to pulse compressed mode which is a high gain operating mode to transmit data over a second range, greater than the first range. In pulse compressed mode a transmitter of the mobile device 102 operates at an increased power level that is above a nominal specified power level. This allows the mobile device 102 to transmit location data, or any other information, a farther distance than in normal operating mode.
The mobile device 102 can transmit a pulse compressed signal 130 at an increased power level over a long distance. The pulse compressed signal 130 is a high power signal that can be communicated over longer distances. Pulse compressing consists of spreading the signal out in time to compress the signal in frequency. As a result of the compressing in frequency, all the energy of the signal is concentrated into a high gain pulse; hence, producing a pulse compressed signal. The mobile device 102, in accordance with the embodiments of the invention, can then transmit the pulse compressed signal 130 at a high than normal gain and over a longer transmit interval while mitigating overheating due to the high power transmission. The combination of pulse compression and high gain transmission allows the signal to be transmitted further, which in the case of emergency situations allows a mobile device to provide location information outside a normal coverage area.
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Briefly, the mobile communication device 102 can reliably send data in a high-gain pulse compressed mode without damaging the power amplifier of the transmitter 140 due to overheating. For example, if the power amplifier is operating at a higher power than it's nominal specification, excess heat will be generated that eventually reduces the efficiency of the transmitter. To prevent overheating, the processor 145 assesses the temperature of the transmitter 140 and evaluates a temperature margin based on a data size of the data, such as short messaging service (SMS) data, from the table 160. The table 160 identifies a temperature margin for the transmitter 140 as a function of data size and current transmitter temperature. The processor 145 can then control a transmitting of the data at the increased power level in view of the temperature margin.
As an example, the mobile communication device 102 can send short messaging service (SMS) data for emergency based or location type applications. The SMS data can be represented as a pulse compressed signal 130. The processor 145 can continually transmit the pulse compressed signal 130 until the transmitter 140 (e.g. power amplifier) reaches a temperature threshold. Upon the transmitter reaching the temperature threshold, the processor 145 can temporarily pause transmitting. The processor 145 can restart transmitting when a temperature margin has been reached. Notably, the processor 145 monitors a temperature from the temperature sensor 208 and controls the transmitting of data using a temperature profile stored in the table 160 to prevent overheating. In particular, the processor 145 evaluates a size of the data, and based on the size of the data and a data rate supported by the transmitter 140, determines a temperature margin for transmitting the data from the table 160. The temperature margin is included in the table 160, which the processor 145 can look up given a current transmitter temperature and data size.
Referring to
At step 201, the method 200 can start. As an example, the method can start in a state wherein a user of a mobile device is in an emergency situation outside of a coverage area or wireless network range and desires to send an emergency beacon transmission. The method 200 can also start in a state wherein a user is within a coverage area or a local area network though poor signal strength conditions prevent the user from sending messages.
At step 210, the processor 145 can determine if the transmitter is sending data at an increased power level. For example, in normal operating mode, the transmitter operates in low power mode. In high-gain pulse compressed mode the transmitter 140 operates at an increased power level. In practice the user may select the operating mode, or the operating mode can be automatically selected, such as selecting the high-gain pulse mode in response to sending an emergency message, wherein the message contains data such as the location of the mobile device 102.
At step 220, the processor 145 can determine a data size of the data. In one arrangement, the data size can be specified as bytes. In another arrangement the data size can be specified as word lengths specific to the processor 145. At step 230, the processor 145 can determine a data rate of the wireless communication device. As an example, the data rate may be specified as 300 Kbps for CDMA, 144 Kbps for TDMA, or 10-100 Mpbs for WLAN. Notably, the data rate is specific to the transmitter 140 and supporting infrastructure. Moreover, the transmitter 140 may also support multiple data rates.
At step 240, the processor 145 can calculate the transmission time from the data size and the data rate. The transmission identifies the amount of time it takes for the transmitter 140 to send the data at the specified data rate given the data size. At step 250, the processor 145 can evaluate a temperature margin for the transmitter operating at the increased power level in view of a transmission time of the data. For example, the processor 145 can look up the temperature margin from the table 160 given the transmission time.
At step 260, the processor 145 can control a transmitting of the data at the increased power level based on the temperature margin to protect the transmitter from excessive heat build-up due to transmitting at the increased power level. In order to prevent overheating of the transmitter 140, data is only transmitted when the temperature margin is positive. Notably, the processor 145 can control the outflow of data to the transmitter 140 to prevent overheating of the power amplifier. The step 260 of controlling the transmitter 140 can include increasing or decreasing a continuous outflow of the data during the transmitting based on the data size. At step 261, the method can end.
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At step 251, the processor 145 can check a present temperature of the transmitter when ready to transmit the data. For example, referring back to
The temperature margin identifies when the transmitter 140 will reach a temperature threshold, at which point a transmission efficiency is reduced. Referring to FIG. 8, a more detailed illustration of the temperature profile 219 of
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At step 410, the processor 145 can determine the time it takes to reach a predetermined threshold. For example, the predetermined temperature threshold may be a maximum junction temperature, such as 85°. Referring back to
In one arrangement, at step 413, the processor 145 can send the file to an outbox. The data in the outbox can be sent to the transmitter in accordance with the data flow established by the processor 145. The processor 145 can continue to monitor the outflow of data from the outbox to the transmitter 140 during transmission. In such regard, the processor prevents the power amplifier of the transmitter 140 from overheating without shutting down the transmitter 140.
Referring to
Where applicable, the present embodiments of the invention can be realized in hardware, software or a combination of hardware and software. Any kind of computer system or other apparatus adapted for carrying out the methods described herein are suitable. A typical combination of hardware and software can be a mobile communications device with a computer program that, when being loaded and executed, can control the mobile communications device such that it carries out the methods described herein. Portions of the present method and system may also be embedded in a computer program product, which comprises all the features enabling the implementation of the methods described herein and which when loaded in a computer system, is able to carry out these methods.
While the preferred embodiments of the invention have been illustrated and described, it will be clear that the embodiments of the invention is not so limited. Numerous modifications, changes, variations, substitutions and equivalents will occur to those skilled in the art without departing from the spirit and scope of the present embodiments of the invention as defined by the appended claims.
