Patent Grant
7623868
This invention generally relates to the provision of wireless network services and specifically to the accommodation of multiple communications protocols, each capable of different data service rates.
In the provision of communication services within a wireless local area network (WLAN), the area is served by multiple interconnected wireless access points located throughout the area forming the network. Such a network may be installed in airports, shopping malls, office buildings, hospitals, and factories, as well as other locations where wireless accessibility may be desired. A wireless access point typically utilizes an omni-directional antenna that communicates with wireless devices, such as computers containing a network interface card (NICs) configured for WLAN communications. Telephones, paging devices, personal data assistants (PDAs), notebooks, and pocket notebooks, as well as other wireless devices, may also communicate using the network. The layout or configuration of the network, i.e., the spacing or separation of the wireless access points, may be determined by the data rate of communications between the network and the wireless devices, the modulation scheme used in those communications, and/or the propagation of communication signals from the wireless access points.
The Institute of Electrical and Electronics Engineers (IEEE) has promulgated three notable standards or communications protocols for WLANs. The first communications protocol, known as 802.11b, was based on proprietary or 2 Megabit per second (Mbps) products utilizing an unlicensed portion of the spectrum found at approximately 2.4 Gigahertz (GHz). The 802.11b communications protocol specifies a modulation scheme known as complementary code keying (CKK) to encode the wireless data in a format that fits within the bandwidth allotted under Federal Communications Commission (FCC) 802.11 direct-sequence spread-spectrum (DSSS) rules. CKK allows communications at data rates of up to 11 Mbps. Although the majority of WLANs in existence today are consistent with the 802.11b communications protocol, 802.11b WLANs are of limited utility since their speed is approximately that of a 10 Mbps Ethernet link.
Concurrent with the approval of the original 802.11b communications protocol, the IEEE approved the 802.11a communications protocol. The 802.11a communications protocol uses a modulation scheme referred to as orthogonal frequency division multiplexing (OFDM) to achieve a data rate of 54 Mbps through a portion of the spectrum located at approximately 5 GHz. A problem facing wireless network providers is that 802.11b and 802.11a WLANs were never intended to be compatible.
More recently, the 802.11g communications protocol has been promulgated, allowing data rates up to 54 Mbps within the 2.4 GHz band using OFDM.
Faced with the evolution of multiple communications protocols and a demand for increased data rates from subscribers, it may be desirable for a wireless network provider to upgrade an existing network, such as an 802.11b WLAN, to provide support for a newer communications protocol, such as 802.11a and/or 802.11g. Moreover, it may be desirable to support future communications protocols having increased data rates.
A concern in supporting more than one communications protocol is that the typical range of or propagation associated with a wireless access point configured for each of the existing communications protocols tends to be different. Such differences may be attributed to differing data rates, the modulation schemes, the number of channels, and/or the carrier frequencies used. in general, for example, the range of conventional 802.11b wireless access points is greater than that of those supporting the 802.11a or 802.11g protocols.
One approach to managing these differences is to reduce the data rate associated with that communications protocol that has the lesser range or propagation, as range tends to be inversely proportional to data rate. Such an approach thwarts the benefits of increased, or higher, data rates and is undesirable in the face of subscriber demands.
Another approach to managing these differences is to attenuate the radiation associated with that communications protocol that has the greater range or propagation. Such an approach may require more wireless access points, as wireless access points would need to be located closer together. Moreover, where an existing network is laid out based on a higher-range protocol, upgrading that network to a faster protocol may require a substantial re-layout of an existing WLAN, and a commensurate increase in costs. Time consuming additional planning may also be required, further increasing costs.
There is a need for a multi-band wireless access point for use in a wireless network capable of supporting multiple communications protocols with ranges that are effectively coextensive. Moreover, there is a need for a multi-band wireless access point capable of compensating for differences in propagation associated with one or more communications protocols.
The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments of the invention and, together with a general description of the invention given above, and the detailed description of the embodiments given below, serve to explain the principles of the invention.
The invention addresses the above-noted desires and needs in the art providing a multi-band wireless access point capable of supporting multiple communications protocols with effectively coextensive ranges for each communications protocol. Moreover, such a multi-band wireless access point compensates for differences in propagation associated with each communications protocol without reducing data rates or relying on attenuation or redistributing access points within an existing network. In accordance with principles of the present invention, a multi-band wireless access point capable of supporting higher data rates and/or higher carrier frequencies at increased ranges is provided.
To this end, a multi-band wireless access point may comprise a first antenna system including at least one antenna and having a first effective range for communication with subscribers using a first communication protocol and a second antenna system including a plurality of antennas generally co-located with the first antenna system and having a second effective range for communicating with subscribers using a second communications protocol wherein the first and second effective ranges are effectively coextensive. A multi-band wireless access point may also comprise a first antenna system including at least one antenna for communication with subscribers using a first communication protocol and a second antenna system including a plurality of antennas generally co-located with the first antenna system for communicating with subscribers using a second communications protocol wherein each of the plurality of antennas in the second antenna system has a greater directivity than the at least one antenna in the first antenna system to compensate for a difference in propagation of the second communications protocol relative to the first communications protocol.
Such multi-band wireless access points having such antenna systems allow upgrading of an existing wireless local area network (WLAN) to communications protocols offering higher data rates without the additional time consuming planning associated with layout due to differences in ranges and/or propagation associated with multiple communications protocols. Moreover, such multi-band wireless access points having such antenna systems may be used to provide for a desired number of channels for particular communications protocols.
For example, wireless access point 10 may be configured for operation using complementary code keying (CKK) to encode wireless data in a format that fits with the bandwidth allotted under Federal Communications Commission (FCC) 802.11 direct-sequence spread-spectrum (DSSS). As such, wireless access point 10 and omni-directional antenna 12 operate at a carrier frequency of 2.4 Gigahertz (GHz), the operation being consistent with FCC 802.11b communications protocol, and allowing wireless devices to communicate at data rates up to 11 Megabits per second (Mbps). Similarly, access point 20 and omni-directional antenna 22 may be configured for operation in accordance with the FCC 802.11a communications protocol, the FCC 802.11a communications protocol specifying a carrier frequency of 5 GHz and capable of supporting data rates up to 54 Mbps.
It has been found that when operating at data throughputs of less than 6 Mbps wireless access points 10 and 20 may have similar ranges and may be able to propagate communications signals to subscribers a similar distance. However, when operating at throughputs of greater than 6 Mbps, wireless access point 10 may be able to propagate communications signals a distance greater than that of wireless access point 20.
As illustrated in
Those skilled in the art will appreciate that differences in range and/or propagation associated with the communications signals from wireless access points 10 and 20 are merely exemplary in nature and are shown for purposes of illustration of needs and desires addressed by the present invention. Such differences may not be indicative of actual differences experienced in particular installations of particular wireless access points. Moreover, those skilled in the art will appreciate that such differences between communications protocols may be attributable not only to differing data rates, but also the modulation schemes, the number of channels, and/or the carrier frequencies used.
Referring to
Multi-band wireless access point 30 comprises a first antenna system 32 including at least one antenna for communicating with subscribers using a first communications protocol and a second antenna system 34 including a plurality of antennas for communicating with subscribers using a second communications protocol. The second antenna system 34 is generally co-located with the first system 32, as illustrated in
For example, the first antenna system 32 may comprise an omni-directional antenna 36, while the plurality of antennas in the second antenna system 34 may be directional antennas 38a-d, where M is the number of antennas and α is the azimuth of each antenna (e.g., M=4, α=90°), defining regions 40a-d, respectively. In such an arrangement of antennas each of the plurality of antennas 38a-d in the second antenna system 34 has a greater directivity than the at least one antenna 36 in the first antenna system 32 thereby compensating for a difference in propagation of the second communications protocol relative to the first communications protocol.
Consistent with the historical example given in
Those skilled in the art will appreciate that ranges 42, 44 need not match or be equivalent. However, it is typically desirable for ranges 42, 44 to be effectively coextensive such that the spacing or layout of multi-band wireless access point 30 is not dependent on a particular communication protocol. Moreover, multi-band wireless access point 30 need not rely a particular protocol. Embodiments of the present invention may support any existing or future communications protocol.
For example, in another embodiment of the present invention having an antenna system like that of
Referring to
Interface 50 may be advantageously designed and manufactured with multiple internal slots 56a-e for plug-in circuit boards, cards, packs or modules containing circuits 58a-e. As configured, circuits 58a-e allow channel assignments and/or frequency planning for the 802.11b and 802.11a or, alternatively, the 802.11b and 802.11g communications protocols. Such circuits 58a-e capable of assigning channels and/or performing frequency planning are capable of being implemented by one of ordinary skill in the art having the benefit of the present disclosure.
For example, circuits 58a-d couple to the plurality of antennas 38a-d, respectively (shown in
Those skilled in the art will appreciate that an interface 50 may include additional slots (not shown) for additional circuits (also not shown) for coupling to differing numbers of antennas for use with combinations of similar or different communications protocols, and performing channel assignments and/or frequency planning as appropriate therefore. An interface 50 may also include empty slots (not shown) for future upgradability. Further, an interface 50 and circuits 58a-e may be combined as unit or module or circuits 58a-e may be combined. Other physical arrangements and/or configurations will readily appear to those skilled in the art.
Referring to
For example, wireless access point 60 may be configured for operation consistent with the 802.11b communications protocol, and has a data throughput of 6 Mbps per channel. Similarly, wireless access point 70 may be configured for operation in accordance with the 802.11a communications protocol, and has a data throughput of 31 Mbps per channel, whereas wireless access point 80 may be configured for operating in accordance with the 802.11g communications protocol, and has a data throughput of 12 Mbps per channel. Such throughputs depend in part on the physical layer associated with the modulation scheme use for each communications protocol, the physical layer requiring 11 Mbps, 54 Mbps, and 54 Mbps for 802.11b, 802.11a, and 802.11g communications protocols, respectively.
As illustrated in
Referring to
Multi-band wireless access point 90 comprises a first antenna system 92 including at least one antenna for communicating with subscribers using a first communications protocol, a second antenna system 94 including a first plurality of antennas for communicating with subscribers using a second communications protocol, and a third antenna system 96 including a second plurality of antennas for communicating with subscribers using a third communications protocol. The second and third antenna systems 94, 96 are generally co-located with the first antenna system 92, as illustrated in
For purposes of explanation, the aforementioned antenna systems 92, 94, 96 associated with the three communications protocols have been broken-out, or apart, on the left side of
For example, the first antenna system 92 may comprise an omni-directional antenna 98, while the first plurality of antennas in the second antenna system 94 may be directional antennas 100a, 100b, where M is the number of antennas and α is the azimuth of each antenna (e.g., M=2, α=180°), defining regions 102a, 102b, respectively, and the second plurality of antennas in the third antenna system 96 may be directional antennas 104a-d, where N is the number of antennas and β is the azimuth of each antenna (e.g., N=4, β=90°), defining regions 106a-d, respectively.
Consistent with the historical example given in
Again, those skilled in the art will appreciate that ranges 108, 110, and 112 need not match or be equivalent. Rather ranges 108, 110, and 112 need only be effectively coextensive such that the spacing or layout of multi-band wireless access point 90 is not dependent on a particular communications protocol. Moreover, multi-band wireless access point 90 need not rely on any particular communications protocol.
In upgrading an existing WLAN, such as an 802.11b WLAN, and providing support for one or more communications protocols offering increased data rates, such as 802.11a and/or 802.11g, additional features may be desirable. These features may, in part, stem from the desirability of maintaining existing wireless access point spacing in a WLAN associated with a particular protocol, such as 802.11b, when upgrading to a higher data rate communications protocol, such as 802.11a and/or 802.11g. Such additional features flow naturally and logically from the embodiments described hereinabove and further define principles of the present invention. Thus, the embodiments of
Referring to
For example, the first plurality of antennas in the first antenna system 122 may be directional antennas 126a-c, where M is the number of antennas and α is the azimuth of each antenna (e.g., M=3, α=120°), defining regions 128a-c, respectively, and the second plurality of antennas in the second antenna system 124 may be directional antennas 130a-c, where N is the number of antennas and β is the azimuth of each antenna (e.g., N=3, β=120°), defining regions 132a-c, respectively. Moreover, the first communications protocol may be 802.11a and the second communications protocol may be 802.11g. Thus, access point 120 has an equal number of high data rate channels for 802.11a and 802.11g. The directivity of each of the antennas in the first and second pluralities of antennas 126a-c, 130a-c provide sufficient additional collective is such that the effective range of 802.11a at higher data rates is effectively coextensive with that of 802.11g while maintaining an existing wireless access point spacing typically associated with 802.11b. Circles 134 and 136 exemplify the effectively coextensive ranges for the first and second antenna systems 122, 124, respectively.
In operation, multi-band wireless access point 120 may provide sustained high data throughput despite an increased number of subscribers per access point in a WLAN. Typical venues of installation for such a multiband wireless access point 120 may be hotspot areas with higher subscriber density, where high data rates and/or many subscribers need to be accommodated. Such areas may include airports, shopping malls, coffee shops, etc.
Referring to
Similar to
For example, the first plurality of antennas in the first antenna system 142 may be directional antennas 146a-c, where M is the number of antennas and α is the azimuth of each antenna (e.g., M=3, α=120°), defining regions 148a-c, respectively, and the second plurality of antennas in the second antenna system 144 may be directional antennas 150a-h, where N is the number of antennas and β is the azimuth of each antenna (e.g., N=8, β=45°), defining regions 152a-h, respectively. Moreover, the first communications protocol may be 802.11b and the second communications protocol may be 802.11a.
Thus, access point 140 provides eight (N=8) high data rate 802.11a channels and three (M=3) low data rate 802.11b channels. The directivity of each of the antennas in the second plurality of antennas 150a-h is such that the effective range of 802.11a at higher data rates is effectively coextensive with that of the first plurality of antennas 146a-c associated with the 802.11b communications protocol while maintaining an existing wireless access point spacing typically associated with 802.11b. The effectively coextensive ranges for the first and second antenna systems 142, 144 are indicated at circles 154, 156, respectively. Typical venues of installation for such a multi-band wireless access point 140 may also be airports, shopping malls, coffee shops, etc.
Although typical historical access points (e.g., see
Referring to
To this end, multi-band wireless access point 160 comprises a first antenna system 166 including a first plurality of antennas for communicating with subscribers using a first communications protocol and a second antenna system 168 including a second plurality of antennas for communicating with subscribers using a second communications protocol. The second antenna system 168 is generally co-located with the first antenna system 166, as illustrated.
For example, the first antenna system 166 may comprise directional antennas 170a, 170b, where M is the number of antennas and α is the azimuth of each antenna (e.g., M=2, α=180°), defining regions 172a, 172b, respectively, while the second antenna system 168 may comprise directional antennas 174a-d where N is the number of antennas and β is the azimuth of each antenna (e.g., N=4, β=90°), defining regions 176a-d, respectively. Antennas 170a and 170b are arranged axially along a centerline 178, along hallway 162 so that the antennas 170a, 170b face opposite ends of hallway 162. Antennas 174a-d are also arranged radically, offset by an angle 180 from centerline 178, along hallway 162 such that antennas 176a and 176b face the opposite end of hallway 162 from antennas 176c and 176d.
As configured, the first standard may be 802.11b and the second standard may be 802.11a. Thus, access point 160 provides two (M=2) low data rate 802.11b channels and four (N=4) high data rate 802.11a channels in the shaped region area within hallway 162. In operation, the directivity of each of the antennas in the plurality of antennas 174a-d is such that the effective range of 802.11a is effectively coextensive with that of 802.11b, as exemplified by regions 176a-d and 172a, 172b, respectively. Those skilled in the art will appreciate that by directing antennas, such as antennas 170a, 170b, 174a-d, in desired directions, such as along or at some angle to the centerline of a hallway, a region of practically any desired shape is obtainable for subscribers.
Using principles of the present invention, existing WLANs or wireless access points may be upgraded to support additional or different communication protocols, often without requiring any changes to the physical layout of wireless access points in a coverage region of a WLAN (e.g., the movement of wireless access points and/or the addition of new wireless access points). Typically, an existing or historical WLAN will include one or more wireless access points each having an antenna system having a first effective range for communicating with subscribers using a first communications protocol. Often, each antenna system utilizes an omni-directional antenna. Upgrading such a WLAN or a wireless access point contained therein comprises installing a second antenna system having a second effective range for communicating with subscribers using a second communications protocol in one or more wireless access points. The second antenna system includes a plurality of antennas and is generally co-located with the first antenna system. The effective ranges for the first and second antennas system are effectively coextensive as described hereinabove.
By virtue of the foregoing, there is thus provided a multi-band wireless access point capable of supporting multiple communications protocols with ranges that are effectively coextensive. Moreover, there is provided a multi-band wireless access point capable of compensating for differences in propagation associated with one or more communications protocols.
While the present invention has been illustrated by the description of the embodiments thereof, and while the embodiments have been described in considerable detail, it is not the intention of the applicants to restrict or in any way limit the scope of the appended claims to such detail. Additional advantages and modifications will readily appear to those skilled in the art. It will be understood that access points consistent with principles of the present invention may be employed in installations of new wireless networks, as well as upgrades of existing networks. Those skilled in the art will also appreciate that the range associated with each communications protocol need not match or be equivalent. In many instances, however, it is desirable for ranges to be effectively coextensive such that the spacing or layout of multi-band wireless access point is not dependent on a particular communication protocol. Further, although known communications protocols have been used for purposes of illustration and explanation, those skilled in the art will appreciate that principles of the present invention may be applied to other, and perhaps unknown, or yet to be developed, communications protocols. Moreover, those skilled in the art will appreciate that antennas and interfaces consistent with principles of the present invention may be configured in the same housing or as separate components. Therefore, the invention in its broader aspects is not limited to the specific details representative apparatus and method, and illustrative examples shown and described. Accordingly, departures may be made from such details without departure from the spirit or scope of applicants' general inventive concept.
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