Abstract:
The present invention discloses a solution for improving scan time in a co-banded mobile communication device. The solution can maintain a set of records within a data store of a co-banded mobile communication device. The set of records can include two or more communication rasters that represent an overlap between frequency bands used by different access technologies supported by the mobile communication device. A frequency band for a first access technology can be scanned for communication rasters allocated for that access technology. For each occupied communication raster, a related record of the set of maintained records can be updated to indicate that the communication raster is occupied. A frequency band for a second access technology can then be scanned within a previously determined time threshold of the first scan. The second scanning attempt can skip those communication rasters indicated as occupied by the set of records.

Description:
BACKGROUND 
     1. Field of the Invention 
     The present invention relates to mobile telecommunication devices and, more particularly, to raster skipping in co-banded mobile communication devices based on previous scans for any band. 
     2. Description of the Related Art 
     Historically, mobile phones have been designed to operate using one access technology, such as Global System for Mobile communication (GSM), Code Division Multiple Access (CDMA), or Time Division Multiple Access (TDMA). Each of the different access technologies utilize a defined set of protocols and techniques to communicate wirelessly over a characteristic set of frequencies of the electromagnetic (EM) spectrum. These frequencies are a valued and finite resource. To maximize usage, reusing spectrum frequencies is common, which is true even among different access technologies. For example, different access technologies can share a portion of the EM spectrum. The wideband version of CDMA (WCDMA), for example, overlaps significantly with GSM frequency ranges. All of the actively used GSM bands have a WCDMA equivalent defined in the latest version of the 3GPP specifications. Co-banded mobile phones currently exist that operate seamlessly across frequency ranges of more than one access technology using suitable protocols for communicating via each supported access technology. For instance, a co-banded mobile phone can support both GSM and WCDMA based communications. Appreciably, co-banded mobile phones are not limited to GSM and WCDMA technologies. Co-banded mobile phones and other mobile communication devices exist currently and more will exist in the future that support two or more access technologies, each of which requires periodic raster scanning. 
     It should be appreciated that mobile phones scan a set of channel segments to find occupied bands associated with a particular access technology and mark those bands that are discovered. A smallest scan-able channel segment that is able to be used for a communication can be referred to as a communication raster. A communication raster composition and specifics can vary based upon an access technology. For example, a Frequency Division Multiple Access (FDMA) access technology (e.g., CDMA) shares the radio spectrum by allocating users different carrier frequencies of a radio spectrum. TDMA access technologies (e.g., GSM, TDMA) allow several users to share the same frequency channel by dividing the signal into different timeslots, each user using their own timeslot. A Space Division Multiple Access (SDMA) takes advantage of spatial separation between users by subdividing a base station&#39;s coverage area into sub-cells and by using directional transmissions to and from a mobile phone so that different spatially located mobile phones can share a frequency channel. Shifting phases is still another technique for dividing a single frequency channel into multiple segments, each of which can be used by a different user to wirelessly communicate. 
     Regardless of which access technology or technologies are being used, scanning for an available communication raster occurs in approximately the same manner. Conventional scanning occurs by ordering the rasters by power level in descending order and checking each one. Checking a raster can require decoding, which determines whether communications are able to be conducted using that raster or not. The ordered rasters are sequentially checked and decoded. If no occupied raster is detected for a given access technology during scanning, the scanning process can be reattempted after a delay period. 
     The large number of rasters resulting from a generous frequency ranges being allocated to different access technologies presents a problem for co-banded mobile phones. Scanning each raster in all frequency ranges for each access technology can result in excessive power usage, which can drain the batteries of handsets. Additionally, the time required to scan through multiple frequency bands increases dramatically from phones that operate in a smaller frequency band, which have to search fewer rasters. This increased scanning time can result in dialing delays, such as a scanning delay that occurs on device power-up, that frustrate users. In areas of dense usage, such as cities, scanning for all communication rasters can be extremely resource intensive. It would be advantageous if scanning times and resource use could be reduced through intelligent raster skipping in co-banded mobile phones, which is not presently being done by any known mobile device. 
     SUMMARY OF THE INVENTION 
     The present invention discloses a solution for raster skipping in co-banded mobile communication devices based on previous scans for any band. That is, when a scan for rasters is performed for a first access technology, such as GSM, an indicator is recorded in an in-device database that signifies whether the raster was occupied by that access technology. That is, the indicator can indicate whether the raster was successfully decoded as a GSM channel. When a second access technology, such as WCDMA, performs a scan soon after the first scan was conducted, overlapping frequency rasters indicated as occupied will be automatically skipped. Thus, two different access technologies that share an overlapping frequency range do not redundantly scan for communication rasters in the same frequency range. 
     It should be appreciated that when a co-banded communication device supports access technologies that have a significant frequency overlap, such as GSM and WCDMA, the disclosed raster skipping solution can reduce scanning times significantly. For example, a typical scanning time for GSM rasters is between five and fifty seconds and a typical scanning time for WCDMA rasters is between less than one second to twenty seconds. Thus, a conventional scanning approach for both GSM and WCDMA rasters would take 5-50 seconds for GSM plus 1-20 seconds for WCDMA for a total of 6-70 seconds. The disclosed solution, in contrast, can be configured to first scan for WCDMA rasters and then for GSM rasters. The WCDMA scan, which can take ten seconds in one instance, can determine that each raster in the frequency range is occupied for WCDMA. Assuming that the WCDMA and GSM frequencies are entirely overlapping, which is currently true in the United States, a GSM scanning attempt will skip every raster, thus taking effectively no time. Hence, the scanning for both WCDMA and GSM is significantly reduced through intelligent channel skipping. 
     The present invention can be implemented in accordance with numerous aspects consistent with the material presented herein. For example, one aspect of the present invention can include a method for improving scan time in a co-banded mobile communication device. The method can include a step of maintaining a set of records within a data store of a co-banded mobile communication device. The set of records can include two or more communication rasters that represent an overlap between frequency bands used by different access technologies supported by the mobile communication device. A frequency band for a first access technology can be scanned for communication rasters allocated for that access technology. For each occupied communication raster, a related record of the set of maintained records can be updated to indicate that the communication raster is occupied. A frequency band for a second access technology can then be scanned within a previously determined time threshold of the first scan. The second scanning attempt can skip those communication rasters indicated as occupied by the set of records. 
     Another aspect of the present invention can include a mobile communication device that includes a first and second set of band components, a scanning component, and a data store. The first set of band components can perform communication operations for wireless communications occurring over a first frequency band. The second set of band components can perform communication operations for wireless communications occurring over a second frequency band. The scanning component can scan the first frequency band and the second frequency band for an available communication raster. The data store can contain a set of records that include communication rasters that represent an overlap between the first frequency band and the second frequency band. When the scanning component performs a scan, the set of records can record when each of the communication rasters is found to be occupied. When searching for available communication rasters, the scanning component can skip rasters determined to be occupied by previous, recent scans. 
     Still another aspect of the present invention can include a co-banded mobile telephone that includes a scanning component. The scanning component can scan two or more frequency bands to find available communication rasters. One or more of the communication rasters in the frequency bands can overlap. The scanning component can skip at least one of the communication rasters in the overlap when scanning one of the frequency bands based upon results of previous scanning attempts performed for a different one of the frequency bands. 
     It should be noted that various aspects of the invention can be implemented as a program for controlling computing equipment to implement the functions described herein, or as a program for enabling computing equipment to perform processes corresponding to the steps disclosed herein. This program may be provided by storing the program in a magnetic disk, an optical disk, a semiconductor memory, or any other recording medium. The program can also be provided as a digitally encoded signal conveyed via a carrier wave. The described program can be a single program or can be implemented as multiple subprograms, each of which interact within a single computing device or interact in a distributed fashion across a network space. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       There are shown in the drawings, embodiments which are presently preferred, it being understood, however, that the invention is not limited to the precise arrangements and instrumentalities shown. 
         FIG. 1  is a schematic diagram of a system that implements raster skipping in co-banded mobile communication devices based on previous scans for any band in accordance with the embodiment of inventive arrangements disclosed herein. 
         FIG. 2  is a flowchart illustrating a method for raster skipping in co-banded mobile communication devices based on previous scans for any band in accordance with the embodiment of inventive arrangements disclosed herein. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       FIG. 1  is a schematic diagram of a system  100  that implements raster skipping in co-banded mobile communication devices based on previous scans for any band in accordance with the embodiment of inventive arrangements disclosed herein. System  100  illustrates a co-banded mobile communication device  110  employing a raster scanning table  132  when scanning for available frequency rasters for establishing a communication channel  162 , over which a wireless communication  160  can occur. The mobile communication device  110  can include a plurality of different bands  112 - 116 . Each band  112 - 116  can represent an access technology associated with a frequency range for operation. The frequency ranges of the bands  112 - 116  can overlap. Raster scanning table  132  takes advantage of this overlap to reduce scanning time across a band  112 - 116  by skipping overlapping frequency rasters, which have been recently checked by another band  112 - 116  and determined to be occupied. 
     More specifically, a band  112 - 116  can submit a scanning request  150  to a scanning component  120  that searches for a communication channel  162  over which communication  160  can be conducted. In one implementation, the scanning component  120  can determine a set of rasters  140  that are to be scanned for the request  150  and an order to be used for the scanning, which is performed by scanning engine  122 . The scanned rasters  140  can exclude those rasters  140  that have recently been checked by any of the bands  112 - 116  and found to be occupied. A Last Update Time  146  and an Occupied  148  column of the table  132  can be used in conjunction with a current time from timer  126  to determine whether an associated raster has been recently scanned and found to be occupied or not. 
     A set of optionally configurable scanning parameters  124  can be used to designate a time-out threshold for rescanning and other scanning specific parameters. For example, the scanning parameters  124  can specify that rasters  140  for a band  112 - 116  are to be ordered sequentially based upon decreasing power levels and scanned from top to bottom. In one embodiment, the scanning parameters  124  can be used to implement complex rules and logic designed to optimize scanning time and channel  162  acquisition. 
     For example, the scanning parameters  124  can specify an order in which different bands are to be scanned. For instance, when used in a region predominately supporting GSM communications, parameters  124  can be set so that a dual-channel device  110  supporting GSM and WCDMA can scan a frequency range for GSM before scanning for WCDMA, since it is likely that GSM will occupy a significant portion, if not all, of the available communication rasters in a shared frequency range. In another instance, when the same device  110  is used in a region predominately supporting WCDMA communications, the parameters  124  can be adjusted to cause the scanning component  120  to scan for WCDMA before scanning for GSM. The rules/settings established by the scanning parameters  124  can vary from extremely basic to an arbitrary complexity. 
     In one embodiment, the table  132  can include frequency rasters  140  for all bands  112 - 116  supported by the device  110 . Columns  142 ,  144  of the table  132  can indicate which rasters  140  are applicable to which bands  112 - 116 . For example, table  132  shows that rasters  1 - 5  can be used for Band A ( 142 ), but that rasters  4 - 5  can be used for Band B ( 144 ). Thus, the first five rasters  140  of table  132  include two overlapping rasters (e.g., Rasters  4  and  5  associated with frequency 1,930 MHz and 1,931 MHz). When the scanning request  150  is for Band B, Raster  4  can be skipped and Raster  5  can be checked, since the table  140  indicates Raster  4  is in use ( 148 ). 
     As used in system  100 , the mobile communication device  110  can be a communication device capable of wireless communication using two or more access technologies, each using a different communication band  112 - 116 . In other words, device  110  is a co-banded communication device. The mobile communication device  110  can include a mobile phone, a two-way radio, a VoIP communication device, a mobile gaming device, a consumer electronic device, an embedded navigation/communication system of a vehicle, and the like. 
     The band components  112 - 116  represent hardware, software, and firmware needed for use of a related communication band. For example, the band components  112 - 116  can include a wireless transceiver, a processor, a modem, and the like, needed for communications involving the related band. Each communication band  112 - 116  will generally correspond to a particular type of access technology. For example, a Band A can be a Global System for Mobile Communications (GSM) communication band used when communicating via GSM access technology. A Band B can be a Wideband Code Division Multiple Access (WCDMA) communication band used when communicating via WCDMA access technology. Other band components  112 - 116  can be associated with Time Division Multiple Access (TDMA) technologies, Code Division Multiple Access (CDMA) technologies, IDEN technologies, and the like. In one embodiment, band components  112 - 116  can be used for personal area network (PAN) communications as well, such as WiFi or WiMax, BLUETOOTH, wireless USB, and the like. Advantages are realized in system  100  in any situation in which a scanning device  110  has an overlapping frequency range of communication rasters for different access technologies. 
     The communication  160  can be any of a variety of communication types, which include full duplex, half duplex, and simplex real time communications. The communication  160  can include voice communication, media streaming communications, Web interaction communications, data exchange communication transactions, and the like. Further, the communication  160  is not limited to real time communications, but can also include near-real time communications (e.g., media streaming using a delay cache to minimize discontinuities) and other communications, such as Web based interactions that are not considered real-time transactions. 
     The communication  160  can occur over any network (not shown) capable of conveying digital content encoded within carrier waves. Content can be contained within analog or digital signals and conveyed through data or voice channels and can be conveyed over a personal area network (PAN) or a wide area network (WAN). The network can include local components and data pathways necessary for communications to be exchanged among computing device components and between integrated device components and peripheral devices. The network can also include network equipment, such as routers, data lines, hubs, and intermediary servers which together form a packet-based network, such as the Internet or an intranet. The network can further include circuit-based communication components and mobile communication components, such as telephony switches, modems, cellular communication towers, and the like. The network can include line based and/or wireless communication pathways. 
     The data store  130  can be physically implemented within any type of hardware including, but not limited to, a magnetic disk, an optical disk, a semiconductor memory, a digitally encoded plastic memory, a holographic memory, or any other recording medium. Data store  130  can be a stand-alone storage unit as well as a storage unit formed from a plurality of physical devices which may be remotely located from one another. Additionally, information can be stored within the data store  130  in a variety of manners. For example, information, such as table  132  information, can be stored within a database structure or can be stored within one or more files of a file storage system where each file may or may not be indexed for information searching purposes. Information stored in data store  130  can also be optionally encrypted for added security. 
       FIG. 2  is a flowchart illustrating a method  200  for raster skipping in co-banded mobile communication devices based on previous scans for any band in accordance with the embodiment of inventive arrangements disclosed herein. Method  200  can be performed in the context of system  100 . 
     The method  200  can begin in step  205 , where a scan initiating event can be detected. In step  210 , the mobile communication device can determine/select a communication band (e.g., an access technology) to be used for a new communication. In step  215 , the mobile communication device can update a raster scanning table to cause past scanning information to time-out as necessary. The following step  220  can include filtering the raster scanning table to include only rasters for the determined communication band. 
     In step  225 , the mobile communication device can filter the raster scanning table to exclude occupied rasters as determined by recent scanning attempts. In step  230 , the remaining rasters can be ordered by decreasing power levels to prepare for scanning and decoding attempts by the mobile communication device. 
     In step  235 , the mobile communication device can select the first ordered raster as shown. In step  240 , the selected raster can be decoded to determine whether the raster is being used by the currently scanned for access technology. If the raster is occupied, the co-banded device can establish that the raster can be used for communications, as shown in step  245 . The method can skip to step  250  if the selected raster is occupied. In step  250 , the mobile communication device can record current time and an occupied indicator in the raster scanning table. In step  255 , a next potential raster can be selected. This next raster can also be decoded, as shown in step  240 . 
     If an entire set of rasters is searched without finding an available raster, the method can optionally repeat steps  220 - 255  for a different access technology. For instance, if no rasters are available for WCDMA communications and if the mobile communication device supports both WCDMA and GSM, the steps  220 - 255  can be repeated for GSM rasters. Appreciably, the mobile communication device can be configured to establish an order of preference to be used to determine a preferential order of use between two or more supported access technologies. Additionally, if all supported bands or access technologies have been scanned and no available raster found, then the scanning can be automatically re-attempted after a previously established delay period occurs. 
     The present invention may be realized in hardware, software, or a combination of hardware and software. The present invention may be realized in a centralized fashion in one computer system or in a distributed fashion where different elements are spread across several interconnected computer systems. Any kind of computer system or other apparatus adapted for carrying out the methods described herein is suited. A typical combination of hardware and software may be a general purpose computer system with a computer program that, when being loaded and executed, controls the computer system such that it carries out the methods described herein. 
     The present invention also may 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. Computer program in the present context means any expression, in any language, code or notation, of a set of instructions intended to cause a system having an information processing capability to perform a particular function either directly or after either or both of the following: a) conversion to another language, code or notation; b) reproduction in a different material form. 
     This invention may be embodied in other forms without departing from the spirit or essential attributes thereof. Accordingly, reference should be made to the following claims, rather than to the foregoing specification, as indicating the scope of the invention.