Abstract:
Briefly, a method of transmitting over a first wireless network a message not addressed to mobile units of the first wireless network, wherein receiving said message causes transmitting stations of the first wireless station to cease transmissions for a predetermined time interval and to enable the access point to be in communication with mobile units or access points of a second wireless network.

Description:
BACKGROUND OF THE INVENTION 
     Modern wireless communication systems such as, for example, wireless local area network (WLAN) communication systems, may include at least one type of device, for example, a mobile unit (MU) and/or an access point (AP). The physical layer of WLAN components may operate in a frequency band assigned to WLAN devices, for example, one of the 2.4 Giga Hertz (GHz) or 5 GHz frequency bands. Thus, an MU or AP that operates in the 2.4 GHz frequency band may not be able to communicate with a MU or an AP that operates in the 5 GHz frequency band. 
     For example, a personal computer (PC) which may be configured to operate as either an AP or MU for both 2.4 GHz and 5 GHz bands may include a dual band network interface card (NIC) able to transmit and receive communications only with one frequency band at a time. In one example, in which the PC may be configured to be an AP operating in both the 2.4 GHz and 5 GHz bands, MUs operating in the 2.4 GHz band may not receive service from the AP when the AP is in communication with MUs operating in the 5 GHz frequency band, and vice-versa. In another example, there may be a gateway device incorporating a WLAN AP, for example operating in the 2.4 GHz band, with the PC configured to operate as an AP in the 5 GHz band. In this system configuration, devices operating in the 5 GHz band may not be able to communicate with the gateway and/or with devices operating in the 2.4 GHz band, and vice-versa. 
     Thus, there is a need to mitigate the above-described disadvantages of dual-band and/or multi-band operation of a wireless network. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       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 accompanied drawings in which: 
         FIG. 1  is a schematic illustration of a wireless network according to an exemplary embodiment of the present invention; and 
         FIG. 2  is a schematic block diagram of a portion of a computer configured as an access point according to an exemplary embodiment of the present invention; 
     
    
    
     It will be appreciated that for simplicity and clarity of illustration, elements shown in the figures have not necessarily been drawn to scale. For example, the dimensions of some of the elements may be exaggerated relative to other elements for clarity. Further, where considered appropriate, reference numerals may be repeated among the figures to indicate corresponding or analogous elements. 
     DETAILED DESCRIPTION OF THE INVENTION 
     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 of ordinary skill 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. 
     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 and/or processes of a computer or computing system, or similar electronic computing device, that manipulate and/or transform data represented as physical, such as electronic, quantities within the computing system&#39;s registers and/or memories into other data similarly represented as physical quantities within the computing system&#39;s memories, registers or other such information storage, transmission or display devices. In addition, the term “plurality” may be used throughout the specification to describe two or more components, devices, elements, parameters and the like. For example, “plurality of mobile unites” describes two or more mobile units. 
     It should be understood that the present invention may be used in a variety of applications. Although the present invention is not limited in this respect, the circuits and techniques disclosed herein may be used in many apparatuses such as units of a wireless communication system. For example, a WLAN may include communication units to transact data between MU and AP. Units of WLAN communication system intended to be included within the scope of the present invention, include, by way of example only, MUs, APs, NICs, dual band NICs, a residential gateway (RG) and the like. 
     Types of WLAN&#39;s intended to be within the scope of the present invention include, although are not limited to, WLAN&#39;s that comply with “IEEE-Std 802.11, 1999 Edition” standard, and in addition “IEEE-Std 802.11b-1999 Supplement to 802.11-1999, Wireless LAN MAC and PHY specifications: Higher speed Physical Layer (PHY) extension in the 2.4 GHz band”, IEEE-Std 802.11a-1999 Supplement to 802.11-1999, Wireless LAN MAC and PHY specifications: Higher speed Physical Layer (PHY) extension in the 5 GHz band” standard, and other supplement standards such as, for example, IEEE 802.11i, IEEE 802.11e and IEEE 802.11g and the like. 
     Turning first to  FIG. 1 , an example of a wireless local area network (WLAN)  100  in accordance with embodiments of the invention is shown. Although the scope of the present invention is not limited to this example, WLAN  100  may include a wireless network  10  that may operate in a frequency band of 2.4 GHz, for example, a wireless network that complies with IEEE-802.11b and/or IEEE-802.11g standard requirements. In addition, WLAN  100  may include a wireless network  20  that may operate in a frequency band of 5 GHz, for example, a wireless network that complies with IEEE-802.11a standard requirements. Furthermore, WLAN  100  may include an access point  30  and the Internet  40 , if desired. Although the scope of the present invention is not limited in this respect, wireless network  10  may include mobile units (MU)  12 ,  14  and a gateway  16  which may incorporate an access point (AP), and wireless network  20  may include MUs  22  and  24 . 
     In operation, AP  30  may include, for example, software applications that may operate with a personal computer (PC). In one embodiment of the invention, AP  30  may serve as an intermediate device of wireless networks  10  and  20 . AP  30  may serve simultaneously as both an AP in wireless network  20  and as an MU in wireless network  10 . In this embodiment, AP  30  may serve for a first predetermined time interval, for example, 90 milliseconds (ms), as an access point for MUs of wireless network  20  and in a second predetermined time interval, for example, 10 ms, as an MU of wireless network  10 . Furthermore, in another embodiment of the invention, AP  30  may be configured to work as a bridge and, under such configuration, may connect MUs  22 ,  24  of wireless network  20  to Internet  40  through gateway  16 . 
     Although the scope of the present invention is not limited in this respect, AP  30  may be configured to operate as a router and may incorporate a firewall capability. In this embodiment of the invention, gateway  16 , for example a residential gateway (RG) that complies with IEEE-802.11b standard, may provide the MUs of wireless networks  10  and  20  with desired services, for example, a wired equivalent privacy (WEP) application for encryption and integrity checking. In alternate embodiments of the invention, AP  30  may be configured to operate with a more robust security suite, if desired. The security suite may be any security suite known to one skilled in the art such as, for example, authentication and key distribution based on IEEE Standard 802.1X-2001 with an associated authentication protocol and confidentiality and integrity suite. Additionally or alternatively, AP  30  may include a firewall module. If a firewall module is used, the firewall may provide protection from devices such as, for example, MUs  12  and  14 , gateway  16 , which operate in wireless network  10  and/or which might make use of the weak security in wireless network  10  in order to attack WLAN  100 . 
     Additionally or alternatively, AP  30  may be configured to operate as both a bridge and a router. According to this alternative or additional feature, AP  30  may accept communications from MUs operating in wireless network  20  that use a WEP key for encryption as well as, but not limited to, communications of MUs that may use higher levels of encryption and secure authentication methods. Furthermore, AP  30  may operate as a bridge for relatively untrusted MUs and as a router and firewall for relatively trusted MUs, if desired. 
     Turning now to  FIG. 2 , a schematic block diagram of an exemplary PC  200  that may be configured as an AP, for example AP  30 , in accordance with embodiments of the invention is shown. Although the scope of the present invention is not limited to this example, PC  200  may include a dual band NIC  210 , a processor  220 , an access point (AP) application  230 , a message generator  240 , a bridge  250 , a buffer  260 , a router  280 , a firewall  290  and an antenna  270 , for example a dipole antenna and the like. 
     In operation, according to an embodiment of the present invention, PC  200  may be configured to operate both as an AP for wireless network  20  and as an MU for wireless network  10 . PC  200  may be configured by executing AP application  230  on processor  220 , if desired. In this configuration, processor  220  may control the operation of NIC  210 . 
     Although the scope of the present invention is not limited in this respect, NIC  210 , for example a dual band NIC that complies with both IEEE-802.11a and IEEE-802.11b standards, may include the capability to operate using a first frequency band  212  of 5 GHz and a second frequency band  216  of 2.4 GHz, if desired. Processor  220 , for example, a reduced instruction set computer (RISC), a complex instruction set computer (CISC), and the like, may switch between NIC  210  bands in order to communicate with at least one of the wireless network  10  and/or  20 . 
     Although the scope of the present invention is not limited in this respect, processor  220  may periodically switch between bands  212 ,  216  of NIC  210 . For example, NIC  210  may transmit a transmission that includes a message on first band  212  to MUs  22 ,  24  of wireless network  20 . The message may be generated by message generator  240  and may include an address, content, and a time interval. For example, the address may be the address of AP  30  or may contain no address of either one of the MUs of network  20 ; the content may be for example, an at least one of, a ready to send (RTS) command, a clear to send (CTS) command, and/or any other command and/or a null message, if desired. In addition, the time interval may be, for example, about 10 ms. The time interval may define a duration for which the MUs  22  and  24  may be instructed to cease transmissions, although the scope of the present invention is not limited in this respect. 
     Although, the scope of the present invention is not limited in this respect, the time interval may be adjusted according to the traffic load placed on wireless networks  10  and  20 . For example, AP  30  may absent itself from wireless network  20  for periods that are long enough to switch to wireless network  10  and receive a beacon from gateway  16 . In the event that the received beacon may indicate buffered communications for any of the AP and/or nodes  22  and  24 , PC  200  may extend the absence period, e.g., by switching back to wireless network  20  and transmitting an additional message, in order to receive the communications and deliver them to the recipient, if desired. 
     Although the scope of the present invention is not limited in this respect, NIC  210  may transmit the message to MUs  22 ,  24  of wireless network  20 . MUs  22 ,  24  may include, for example, a mechanism known to one skilled in the art of IEEE-802.11 as a virtual carrier sense or network allocation vector, although the scope of the present invention is in no way limited in this respect. Upon receipt of the message, the virtual carrier sense of MUs  22 ,  24  may cause MUs  22 ,  24  to cease the transmissions to AP  30  for a predetermined time interval, according to instructions contained in the message. In the predetermined time interval during which the transmissions from MUs  22 ,  24  are halted, processor  220  may switch NIC  210  to second frequency band  216 . Thus, AP  30  may communicate with gateway  16  and may download messages that had been buffered and stored at gateway  16  during the time that AP  30  was in communication with MUs  22 ,  24  of wireless network  20 , if desired. In addition, the AP  30  may transmit to gateway  16  messages previously received from MUs  22  or  24  and buffered at AP  30 , if desired. 
     Furthermore, while AP  30  may communicate with mobile units  22 ,  24  of wireless network  20 , AP  30  may simulate for mobile units  12 ,  14  of wireless network  10  a standby mode and/or a power-saving mode. Thus, transmissions from MU  12 ,  14  and/or transmissions received from the Internet connection may be buffered at gateway  16 . In one embodiment of the present invention, the method used by AP  30  may simulate a power saving mode, e.g., as defined in the IEEE-802.11 standard, for MUs  12 ,  14  of wireless network  10  and for gateway  16 , although the invention is not limited in this respect. 
     Although the scope of the present invention is not limited in this respect, in alternative embodiments of the present invention, PC  200  may be configured to serve as bridge  250  between wireless network  10  and wireless  20 . For example, in this configuration, processor  220  may be switched periodically between the bands of NIC  210 . MUs  22  and  24  of wireless network  20  may be connected to Internet  40  through gateway  16 . The communications from MUs  22 ,  24  may be buffered at buffer  260  and may be transmitted by bridge  250  to gateway  16 , using NIC  210  and antenna  270 . 
     Although the scope of the present invention is not limited in this respect, in another embodiment of the present invention, PC  200  may be configured as a router. In this embodiment, communications from MUs  22 ,  24  may be authenticated at firewall  290  and may be routed by router  280  to Internet  40 . In this embodiment, it should be understood by one skilled in the art that it is not necessary for a firewall to be implemented in order for the router to be implemented. 
     Although the scope of the present invention is not limited in this respect, in another embodiment of the present invention, PC  200  may be configured to be both a router and a bridge. In this configuration, communications to and from gateway  16  and MUs  22 ,  24  may be authenticated at firewall  290 , if implemented, and may be routed by router  280  to buffer  260  and bridge  250 . Furthermore, in this embodiment PC  200  may permit firewall  290  to incorporate some higher levels of security such as, for example, a virtual private network (VPN), to allow communications of MUs with WEP encryption to access data that may be stored in a hard disk of PC  200 , if desired. 
     While certain features of the invention have been illustrated and described herein, many modifications, substitutions, changes, and equivalents will now occur to those skilled in the art. It is, therefore, to be understood that the appended claims are intended to cover all such modifications and changes as fall within the true spirit of the invention.