Abstract:
Briefly, in accordance with one embodiment of the invention, a mobile unit may detect and connect to a wireless local area network, contemplating worldwide multiband networks and multiple regulatory domains, with a shorter searching time.

Description:
BACKGROUND OF THE INVENTION 
   The time required for network connection is one technical parameter indicating performance of a wireless system. With regulatory limitations imposed on wireless communications, a mobile unit obtains regulatory information such as valid frequency channels and transmitting power levels, typically broadcast from the network itself, before connecting to the network. If there is no regulatory information broadcast from the network, or if the mobile unit does not support the regulatory standard, the mobile unit searches available channels using a passive joining method. Such a passive joining method may require some amount of time for the mobile unit to connect to the network, thereby impacting performance of the wireless system. 

   
     DESCRIPTION OF THE DRAWING FIGURES 
     The subject matter regarded as the invention is particularly pointed out and distinctly claimed in the concluding portion of the specification. The invention, however, both as to organization and method of operation, together with objects, features, and advantages thereof, may best be understood by reference to the following detailed description when read with the accompanying drawings in which: 
       FIG. 1  is a block diagram of a wireless local area network in accordance with one embodiment of the present invention; and 
       FIG. 2  is a flow diagram of a method for detecting a wireless local area network in accordance with one embodiment of the present invention. 
   

   It will be appreciated that for simplicity and clarity of illustration, elements illustrated in the figures have not necessarily been drawn to scale. For example, the dimensions of some of the elements are exaggerated relative to other elements for clarity. Further, where considered appropriate, reference numerals have been repeated among the figures to indicate corresponding or analogous elements. 
   DETAILED DESCRIPTION 
   In the following detailed description, numerous specific details are set forth in order to provide a thorough understanding of the invention. However, it will be understood by those skilled in the art that the present invention may be practiced without these specific details. In other instances, well-known methods, procedures, components and circuits have not been described in detail so as not to obscure the present invention. 
   Some portions of the detailed description that follows are presented in terms of algorithms and symbolic representations of operations on data bits or binary digital signals within a computer memory. These algorithmic descriptions and representations may be the techniques used by those skilled in the data processing arts to convey the substance of their work to others skilled in the art. 
   An algorithm is here, and generally, considered to be a self-consistent sequence of acts or operations leading to a desired result. These include physical manipulations of physical quantities. Usually, though not necessarily, these quantities take the form of electrical or magnetic signals capable of being stored, transferred, combined, compared, and otherwise manipulated. It has proven convenient at times, principally for reasons of common usage, to refer to these signals as bits, values, elements, symbols, characters, terms, numbers or the like. It should be understood, however, that all of these and similar terms are to be associated with the appropriate physical quantities and are merely convenient labels applied to these quantities. 
   Unless specifically stated otherwise, as apparent from the following discussions, it is appreciated that throughout the specification discussions utilizing terms such as processing, computing, calculating, determining, or the like, refer to the action or processes of a computer or computing system, or similar electronic computing device, that manipulate or transform data represented as physical, such as electronic, quantities within the registers or memories of the computing system into other data similarly represented as physical quantities within the memories, registers or other such information storage, transmission or display devices of the computing system. 
   Embodiments of the present invention may include apparatuses for performing the operations herein. This apparatus may be specially constructed for the desired purposes, or it may comprise a general purpose computing device selectively activated or reconfigured by a program stored in the device. Such a program may be stored on a storage medium, such as, but is not limited to, any type of disk including floppy disks, optical disks, CD-ROMs, magnetic-optical disks, read-only memories (ROMs), random access memories (RAMs), electrically programmable read-only memories (EPROMs), electrically erasable and programmable read only memories (EEPROMs), flash memory, magnetic or optical cards, or any other type of media suitable for storing electronic instructions, and capable of being coupled to a system bus for a computing device. 
   The processes and displays presented herein are not inherently related to any particular computing device or other apparatus. Various general purpose systems may be used with programs in accordance with the teachings herein, or it may prove convenient to construct a more specialized apparatus to perform the desired method. The desired structure for a variety of these systems will appear from the description below. In addition, embodiments of the present invention are not described with reference to any particular programming language. It will be appreciated that a variety of programming languages may be used to implement the teachings of the invention as described herein. 
   In the following description and claims, the terms coupled and connected, along with their derivatives, may be used. In particular embodiments, connected may be used to indicate that two or more elements are in direct physical or electrical contact with each other. Coupled may mean that two or more elements are in direct physical or electrical contact. However, coupled may also mean that two or more elements may not be in direct contact with each other, but yet may still cooperate or interact with each other. 
   It should be understood that embodiments of the present invention may be used in a variety of applications. Although the present invention is not limited in this respect, the circuits disclosed herein may be used in many apparatuses such as in the transmitters and receivers of a radio system. Radio systems intended to be included within the scope of the present invention include, by way of example only, wireless local area networks (WLAN) devices and wireless wide area network (WWAN) devices including wireless network interface devices and network interface cards (NICs), base stations, access points (APs), gateways, bridges, hubs, cellular radiotelephone communication systems, satellite communication systems, two-way radio communication systems, one-way pagers, two-way pagers, personal communication systems (PCS), personal computers (PCs), personal digital assistants (PDAs), and the like, although the scope of the invention is not limited in this respect. 
   Types of wireless communication systems intended to be within the scope of the present invention include, although not limited to, Wireless Local Area Network (WLAN), Wireless Wide Area Network (WWAN), Code Division Multiple Access (CDMA) cellular radiotelephone communication systems, Global System for Mobile Communications (GSM) cellular radiotelephone systems, North American Digital Cellular (NADC) cellular radiotelephone systems, Time Division Multiple Access (TDMA) systems, Extended-TDMA (E-TDMA) cellular radiotelephone systems, third generation (3G) systems like Wide-band CDMA (WCDMA), CDMA-2000, and the like, although the scope of the invention is not limited in this respect. 
   Referring now to  FIG. 1 , a wireless local area network communication system in accordance with one embodiment of the present invention will be discussed. In the WLAN communications system  100  shown in  FIG. 1 , a mobile unit  110  may include a wireless transceiver  112  to couple to an antenna  118  and to a processor  114  to provide baseband and media access control (MAC) processing functions. Processor  114  in one embodiment may comprise a single processor, or alternatively may comprise a baseband processor and an applications processor, although the scope of the invention is not limited in this respect. Processor  114  may couple to a memory  116  which may include volatile memory such as DRAM, non-volatile memory such as flash memory, or alternatively may include other types of storage such as a hard disk drive, although the scope of the invention is not limited in this respect. Some portion or all of memory  116  may be included on the same integrated circuit as processor  114 , or alternatively some portion or all of memory  116  may be disposed on an integrated circuit or other medium, for example a hard disk drive, that is external to the integrated circuit of processor  114 , although the scope of the invention is not limited in this respect. 
   Mobile unit  110  may communicate with access point  122  via wireless communication link  132 , where access point  122  may include at least one antenna  120 . In an alternative embodiment, access point  122  and optionally mobile unit  110  may include two or more antennas, for example to provide a spatial division multiple access (SDMA) system or a multiple input, multiple output (MIMO) system, although the scope of the invention is not limited in this respect. Access point  122  may couple with network  130  so that mobile unit  110  may communicate with network  130 , including devices coupled to network  130 , by communicating with access point  122  via wireless communication link  132 . Network  130  may include a public network such as a telephone network or the Internet, or alternatively network  130  may include a private network such as an intranet, or a combination of a public and a private network, although the scope of the invention is not limited in this respect. Communication between mobile unit  110  and access point  122  may be implemented via a wireless local area network (WLAN), for example a network compliant with an Institute of Electrical and Electronics Engineers (IEEE) standard such as IEEE 802.11a, IEEE 802.11b, HiperLAN-II, and so on, although the scope of the invention is not limited in this respect. In another embodiment, communication between mobile unit  110  and access point  122  may be at least partially implemented via a cellular communication network compliant with a 3GPP standard, although the scope of the invention is not limited in this respect. 
   Referring now to  FIG. 2 , a method for detecting a wireless local area network in accordance with the present invention will be discussed. The method  200  of  FIG. 2  in one embodiment may be implemented by mobile unit  110  of  FIG. 1  and may be, for example, tangibly embodied as instructions stored in memory  116  and executed by processor  114 , although the scope of the invention is not limited in this respect. Method  200  may initiate at block  210  where mobile unit  110  may power up and start searching for an access point  122  with which to communicate, and may communicate in a manner compliant with an IEEE standard such as the IEEE 802.11a standard or the like, although the scope of the invention is not limited in this respect. In one embodiment, mobile unit  110  may be arranged to operate in one or more regulatory regions, and may start with a preferred searching region at block  212 , for example the United States region, the Europe Region, the Japan region, and so on. The preferred searching region may be selected in one or more ways, for example the user may select a preferred region. Alternatively, the region in which mobile unit  110  previously operated may be the initially selected preferred region. In another alternative embodiment, the preferred region may be selected with a default setting which may be for example stored in memory  116 , although the scope of the invention is not limited in this respect. 
   Mobile unit  110  at block  214  may then tune to an available channel in the preferred region, and may look for any IEEE 802.11 wireless network activity such as any traffic, including data packets or management packets, for one or more available channels in the preferred region, and optionally until all available channels are scanned. For each channel, a determination may be made at block  216  whether any IEEE 802.11 activity or packets are detected, and if not, a determination may be made at block  220  whether a maximum waiting time has been reached. If a maximum waiting time has been reached, method  200  may continue at block  234  which is discussed, below. 
   In the event IEEE 802.11 activity or packets are detected at block  216 , regions that are do not operate on the current frequency may be eliminated at block  218 , if possible. For example, if IEEE 802.11 activity is detected at block  216  on a United States region frequency band, then the Japan region may be eliminated since there are no mutual frequency bands in the United States region and the Japan region. A determination may be made at block  222  whether a network may be identified from the detected IEEE 802.11 activity or packets. For example, if a beacon from access point  122  is detected, mobile unit  110  may determine whether the beacon includes a desired service set identifier (SSID) which may be used, for example, to differentiate one wireless local area network from another wireless local area network. If the SSID is a desired SSID, then the searching process of method  200  may be exited, and mobile unit  100  may process association and connect with access point  122  at block  226 , although the scope of the invention is not limited in this respect. 
   In the event a desired network is not identified at block  222 , the current channel may be considered a valid channel, and a mobile unit  110  may broadcast a probe request with information indicating a desired network identification, for example an SSID. In one embodiment, the probe request may be transmitted using a safe transmission power level, although the scope of the invention is not limited in this respect. A determination may be made at block  228  whether a response is received in reply to the probe request, and if so, then the searching process of method  200  may be exited, and mobile unit  100  may process association and connect with access point  122  at block  230 , although the scope of the invention is not limited in this respect. If no reply to the probe request is received, then the current channel may be eliminated at block  232  for a predetermined time period, allowing for rescanning of the current channel after the predetermined time period to allow for a case in which the network environment may change. In an alternative embodiment, two or more probe requests may be transmitted prior to elimination of the current channel at block  232 , although the scope of the invention is not limited in this respect. 
   A determination may be made at step  234  whether all channels have been scanned in a current, non-eliminated region. In the event not all channels have been scanned, mobile unit  110  may tune to another channel within a non-eliminated region at block  238 , and method  200  may continue at block  216  on the next tuned channel. In the event all channels have been scanned, another scan cycle may be started at block  236  within the limited, or valid, regions, using a predetermined time interval, and method  200  may continue accordingly at block  216 . In one embodiment, complete network activity information might not be determined via method  200  since the searching process may exit in the middle of the scanning. However it may be provided to a host of mobile unit  110 , for example the operating system of mobile unit  110 , once mobile unit  110  completes association with access point  122  through a complete network scanning for all channels although the scope of the invention is not limited in this respect. 
   Although the invention has been described with a certain degree of particularity, it should be recognized that elements thereof may be altered by persons skilled in the art without departing from the spirit and scope of the invention. It is believed that the wireless local area network detection of the present invention and many of its attendant advantages will be understood by the forgoing description, and it will be apparent that various changes may be made in the form, construction and arrangement of the components thereof without departing from the scope and spirit of the invention or without sacrificing all of its material advantages, the form herein before described being merely an explanatory embodiment thereof, and further without providing substantial change thereto. It is the intention of the claims to encompass and include such changes.