Patent Application
20080182528
The present invention relates to wireless local area networks (WLANs) and other networks incorporating RF elements and/or RF devices. More particularly, the present invention relates to methods for improving the placement of RF devices, such as access points, within an indoor or outdoor environment.
There has been a dramatic increase in demand for mobile connectivity solutions utilizing various wireless components and WLANs. This generally involves the use of wireless access points that communicate with mobile devices using one or more RF channels (e.g., in accordance with one or more of the IEEE 802.11 standards).
At the same time, RFID systems have achieved wide popularity in a number of applications, as they provide a cost-effective way to track the location of a large number of assets in real time. In large-scale applications such as warehouses, retail spaces, and the like, many RFID tags may exist in the environment. Likewise, multiple RFID readers are typically distributed throughout the space in the form of entryway readers, conveyer-belt readers, mobile readers, and the like, and these multiple components may be linked by network controller switches and other network elements.
Because many different RF transmitters and other components may exist in a particular environment, the deployment and management of such systems can be difficult and time-consuming. For example, it is desirable to configure access points and other such RF components such that RF coverage is complete within certain areas of the environment. Accordingly, there exist various RF planning systems that enable a user to predict indoor/outdoor RF coverage. The result is a prediction as to where the transmitters should be placed within the environment. Such systems are unsatisfactory in a number of respects, however, as they often are unable to efficiently process the presence of gaps and holes in wireless coverage.
In general, systems and methods are provided for optimizing the placement of RF components (e.g., access points, access ports, RF antennas) within an environment. According to various embodiments, systems and methods are provided for improving the placement of RF devices each having a position and a coverage area within an environment. The system operates by identifying a gap in the environment that is outside the coverage areas of the RF. A size of the gap and a relative direction of the gap from the position of one of the RF devices are determined. The position of the RF device is then moved in a direction corresponding to the relative direction to thereby reduce the size of the gap. The process can be repeated any number of times until a suitable placement scheme is achieved.
This summary is provided to introduce a selection of concepts in a simplified form that are further described below in the detailed description. This summary is not intended to identify key features or essential features of the claimed subject matter, nor is it intended to be used as an aid in determining the scope of the claimed subject matter.
A more complete understanding of the present invention may be derived by referring to the detailed description and claims when considered in conjunction with the following figures, wherein like reference numbers refer to similar elements throughout the figures.
The following description generally relates to methods and systems for optimizing the placement of RF components within an environment to maximize RF coverage. In this regard, the following detailed description is merely illustrative in nature and is not intended to limit the embodiments of the invention or the application and uses of such embodiments. Furthermore, there is no intention to be bound by any expressed or implied theory presented in the preceding technical field, background, brief summary or the following detailed description.
Embodiments of the invention may be described herein in terms of functional and/or logical block components and various processing steps. It should be appreciated that such block components may be realized by any number of hardware, software, and/or firmware components configured to perform the specified functions. For example, an embodiment of the invention may employ various integrated circuit components, e.g., memory elements, digital signal processing elements, logic elements, look-up tables, or the like, which may carry out a variety of functions under the control of one or more micro-processors and/or other control devices. Similarly, other embodiments may be practiced using any number of data transmission and data formatting protocols in addition to those described herein. The systems and techniques described herein are therefore intended merely as exemplary embodiments.
For the sake of brevity, conventional techniques related to signal processing, data transmission, signaling, network control, the 802.11 family of specifications, wireless networks, RFID systems and specifications, and other functional aspects of the systems (and the individual operating components of the systems) may not be described in detail herein. Furthermore, the connecting lines shown in the various figures contained herein are intended to represent example functional relationships and/or physical couplings between the various elements. It should be noted that many alternative or additional functional relationships or physical connections may be present in equivalent embodiments.
The following description refers to elements or nodes or features being “connected” or “coupled” together. As used herein, unless expressly stated otherwise, “connected” means that one element/node/feature is directly joined to (or directly communicates with) another element/node/feature, and not necessarily mechanically. Likewise, unless expressly stated otherwise, “coupled” means that one element/node/feature is directly or indirectly joined to (or directly or indirectly communicates with) another element/node/feature, and not necessarily mechanically. The term “exemplary” is used in the sense of “example,” rather than “model.” Although the figures may depict example arrangements of elements, additional intervening elements, devices, features, or components may be present in an embodiment of the invention.
Referring to the conceptual plan view shown in
Environment 103, which may correspond to a workplace, a retail store, a home, a warehouse, or any other such space, will typically include various physical features 104 that affect the nature and/or strength of RF signals received and/or sent by AP 114. Such feature include, for example, architectural structures such as doors, windows, partitions, walls, ceilings, floors, machinery, lighting fixtures, and the like.
Boundary 102 may have any arbitrary geometric shape, and need not be rectangular as shown in the illustration. Indeed, boundary 102 may comprise multiple topologically unconnected spaces, and need not encompass the entire workplace in which AP 114 is deployed. Furthermore, concepts described herein are not limited to two-dimensional layouts; they may be extended to three dimensional spaces as well.
AP 114 is configured to wirelessly connect to one or more mobile units (MUs) (not shown) and communicate one or more switches, routers, or other networked components via appropriate communication lines (not shown). Any number of additional and/or intervening switches, routers, servers, and other network components may also be present in the system.
At any given time, 114 may have a number of associated MUs, and is typically capable of communicating with through multiple RF channels. This distribution of channels varies greatly by device, as well as country of operation. For example, in accordance with a typical 802.11(b) deployment there are generally fourteen overlapping, staggered channels, each centered 5 MHz apart in the RF band.
As described in further detail below, AP 114 includes hardware, software, and/or firmware capable of carrying out the functions described herein. Thus, AP may comprise one or more processors accompanied by storage units, displays, input/output devices, an operating system, database management software, networking software, and the like. Such systems are well known in the art, and need not be described in detail here.
For wireless data transport, AP 114 may support one or more wireless data communication protocols—e.g., RF; IrDA (infrared); Bluetooth; ZigBee (and other variants of the IEEE 802.15 protocol); IEEE 802.11 (any variation); IEEE 802.16 (WiMAX or any other variation); Direct Sequence Spread Spectrum; Frequency Hopping Spread Spectrum; cellular/wireless/cordless telecommunication protocols; wireless home network communication protocols; paging network protocols; magnetic induction; satellite data communication protocols; GPRS; and proprietary wireless data communication protocols such as variants of Wireless USB.
Referring now to
Coverage areas 112A-B, then, represent those areas within boundary 102 that can be expected to provide an acceptable level of service. This “acceptable” level of service may correspond to those regions wherein received signal levels are expected to reliably exceed a minimally-acceptable level (e.g. wherein the observed or predicted RSSI value exceeds an acceptable minimum value). Alternatively, other metrics of “acceptable” service could be used.
As shown, a gap 202 exists between coverage areas 112A and 112B, and a gap 204 exists between boundary 102 and the outer reaches of areas 112A and 112B. APs 114A and/or 114B can be appropriately relocated to optimal (or at least improved) positions based on a coverage metric, which may be iteratively recalculated adaptively until the metric reaches a predetermined coverage metric threshold (or simply “threshold”).
The coverage metric may be any quantitative or qualitative measure that identifies gaps within an area at any given time. In one embodiment, for example, the coverage metric is equal to the total planar area of all gaps within the relevant area. The coverage metric may also take into account and assist with reducing overlapping coverage areas. In an alternate embodiment, the coverage metric may relate to how much RF coverage overlap can be allowed.
The coverage metric calculations can be thusly computed based on gaps in RF coverage present in the environment—which change size and/or position as the various APs 114 are moved to reduce or otherwise change the coverage metric within that area. In the illustrated embodiment, for example, two gaps are present: gap 202 and gap 302. Each of these gaps has planar geometrical attributes such as area, shape, centroid, and the like, all of which may be calculated (e.g., using suitable hardware and software) given the shapes of coverage areas 112.
Operation of the system generally proceeds as follows. First, modeling information regarding the environment and components within the environment 103 are collected to produce a spatial model. This information may include, for example, building size and layout, country code, transmit power per AP, antenna gain, placement constraints, transmit power constraints, data rate requirements, coverage requirements, barrier information, and the like. In this regard, the environment 103 within boundary 102 may be discretized or quantized into a grid or other data abstraction for computational purposes. The size and shape of the coverage areas 112 within boundary 102 are then determined for the set of APs 114 using any of the techniques described above. Any contiguous gaps (e.g., gaps 202 and 302) within environment 103 are then identified, and the shapes, sizes, and/or any other suitable attributes for each of those gaps can be computed. The coverage metric is then computed, based, for example, on the total area of the identified gaps (e.g. gaps 202 and 302 in
Once the coverage metric is computed, the system determines a new position for one or more of the APs—e.g., the most recent AP to enter the environment, or the AP that is closest to a corner or other point of reference. Next, the AP (e.g., AP 114B) is moved within the spatial model to that new position. The new position may be determined by defining an angular direction in which the AP should move, as well as a step size that defines the scalar distance of movement.
The direction and quantity of AP movement during any iteration may be specified in any suitable manner based on gap sizes and/or the relative locations of gaps and APs. In one embodiment, the angular direction of AP movement corresponds to a line leading from the current placement of the AP to an extrema (i.e., a point on the perimeter) of one of the gaps. In a particular embodiment, the angular direction is defined by the point on the perimeter of the gap that is farthest away from the current position of the AP. Referring again to
The distance that the AP is moved may be selected in accordance with any of various principles to achieve the desired stability and convergence time. In various embodiments, the distance is based upon the size of the gap or the distance from the AP to the gap. In various embodiments, an average gap metric can be computed based on an integration or discrete summation of the distances from the AP to one or more points within a gap. This summation may be based upon the entire area of the gap, or may be limited to the points located on the periphery of the gap. In still other embodiments, an average hole size (“W”) of all the gaps present within environment 103 may be computed, and the step size can be determined based upon this quantity. Such embodiments may thereby base the distance moved on the relative size of the hole of interest with respect to the total area of holes to be eliminated, thereby potentially reducing deleterious effects upon other holes within environment 103. The distance may also be adjusted based upon building materials, objects in the vector path and/or other factors as appropriate.
After the direction and distance of vector 254 or 256 is conceptualized, the corresponding AP 114A or 114B can be moved accordingly. Although
The methods described above may be performed in hardware, software, firmware or any combination thereof. For example, in one embodiment one or more software modules are configured to be stored on a digital storage medium (e.g. a disk, memory and/or the like) and executed on a general purpose computer having a processor, memory, I/O, display, and/or other suitable components.
While at least one example embodiment has been presented in the foregoing detailed description, it should be appreciated that a vast number of variations exist. It should also be appreciated that the example embodiment or embodiments described herein are not intended to limit the scope, applicability, or configuration of the invention in any way. Rather, the foregoing detailed description will provide those skilled in the art with a convenient road map for implementing the described embodiment or embodiments. It should be understood that various changes can be made in the function and arrangement of elements without departing from the scope of the invention, where the scope of the invention is defined by the claims, which includes any and all known and foreseeable equivalents at the time of filing this patent application.
