Custom WLAN Approach

    Usually, wireless networks are the prerogative of open spaces (warehouses, workshops, squares) or small rooms (apartments and small offices). Building a Wi-Fi network in a large office / institution building / hotel / hospital / school is a serious headache and a lot of money. But the recipes are here, and very interesting. We’ll talk about them.

    Traditionally, wireless in office centers, institutions, hotels / hospitals / schools, etc. unfolds on the principle of “points in the corridor - users in rooms”. First of all, this is due to the rather high price of the Enterprise-class access point and the related desire to put as many users as possible on one point. Plus, running a cable into the corridor is usually simpler than into rooms. But it is precisely this approach that causes problems.


    At firstIt is rather difficult to provide high-quality radio coverage. The buildings are large, have a rather complicated architecture, many internal partitions, fire safety rules require firewalls, in pre-revolutionary buildings (and residences of a number of government agencies) wall thickness is measured in meters - all this complicates the signal passage. Even hotels, usually built on the principle of “a hall, a direct corridor and doors on both sides”, have their own characteristics: bathrooms are most often located closer to the corridor (and this is a tile on a grid, mirrors, a lot of metal), on the walls of corridors there are often various decorations and the same mirrors (and the reflective coating of the mirror, essence, metal), the walls separating the rooms from the corridors should be fireproof (like doors). At the same time, along the corridor the signal propagates quite well,

    Secondly, the terrible word "repair". Any SKSnik with experience can tell about customers who first made expensive repairs with Italian marble, and then realized that they were laying a network. The same thing happens with the wireless - they did not forget to lay the SCS, but after the change they decided to “attach” Wi-Fi - “But we do not allow laying a new cable!” To provide human coverage in such conditions is almost an unrealistic task. An example would be a project in a small building (4 floors, atrium), in which one point provided 80% of the coverage, and another 9 huddled along the “permissible” corners, closing the remaining holes. Again, issues of aesthetics (in an expensive business center or hotel will not tolerate the sticking out “horns” of powerful antennas) and security (in hospitals and schools).

    Thirdly, more than 50% of the cost of a project to create a wireless network in a building is the cost of the passive part and the associated work. If they could have been avoided, the cost and terms of the project could have been completely reduced, and even the question of point 2 could be practically closed.

    The solution, however, is quite obvious. Remember, at the time, 3Com (possibly other vendors) released an interesting product called NJ100 ?


    How does this relate to wireless?

    As you can see from the picture, this is a switch with 4 Ethernet RJ45 ports (actually with 5), made in the form of a standard SCS outlet. Everything ingenious is simple! Wireless manufacturers have followed the same principle by developing low-cost access points that mount directly onto a wall outlet (WallPlate AP).

    The points are equipped with built-in antennas of low power (sufficient to cover 1-3 adjacent rooms) and designed to work from the height of the wall outlet (and not from the ceiling), they can additionally have several RJ-45 and RJ-11 ports (phone forwarding), do not require configurations before installation, can work both with the controller and autonomously. At the same time, the installation procedure is usually simplified as much as possible so that an unprepared user handles it and comes to a few steps: remove the outlet, put the point in place, connect the cable, insert (and often just click on) the point in the place of installation.

    The procedure for setting the “outlet” point is extremely simple.

    All of the above radically changes the whole approach to planning - instead of thinking about how to break into a room from a corridor with a signal, how to get a cable to work out better, and not to affect repairs, how to ensure fault tolerance and normal channel planning - we just set the points right where you need coverage. They can be placed in work rooms, hotel rooms, halls, meeting rooms, conference rooms, corridors, so to speak, “on the client side”. On the contrary, walls and other obstacles begin to help us - they weaken the interference between neighboring points, which simplifies channel planning (recall, there are only three disjoint channels in the 2.4 GHz band). Also, virtually no cabling is required, which eliminates the additional costs of SCS,

    The use of “outlet” points radically changes the approach to radio planning. For the better.

    Today, there are two subspecies of WallPlate AP solutions. The first works on top of traditional wired Ethernet (for those who already have SCS but no WLAN). The second is suitable for those who do not even have SCS, but have a PBX-based telephone network - in this case, DSL is used.

    Class One: over Ethernet.

    In principle, everything is clear here - we are building a superimposed wireless network on top of the existing Ethernet network at points of a special form factor. The most famous solutions are (in order of appearance on the world stage): HP MSM317 (the result of the acquisition of HP by Colubris, a hotel specialist), Ruckus Wireless ZoneFlex 7025 and Motorola AP-6511 . Common characteristics for them are: low price (because there will be many points — small antennas are weak), built-in antenna, compactness, ease of installation, PoE power, the ability to provide Ethernet ports (including one port with PoE) . However, the same points on the outside radically differ inside, and each one is most optimal for its scenario.

    From left to right: Motorola AP-6511 (with and without mini-switch), HP MSM317, Ruckus Wireless ZoneFlex 7025

    HP, in fact, produces a typical "thin" access point in a compact design. MSM317 runs exclusively on a controller. This, on the one hand, is very convenient: you do not need to configure points before installation, dynamic control of radio coverage and channels appears, it is easy to replace, everything is perfectly controlled remotely through HP ProCurve Manager. Colubris controllers themselves provide the broadest possibilities in terms of user authentication, organizing hotspots and collecting data for billing. The most remarkable thing is that, like the 3Com switch discussed earlier, the point is mounted in a standard socket for an SCS socket! However, there are also limiting factors. 802.11n is not supported (it simply wasn’t available at the time of release), you cannot hide Ethernet ports from the user, there is no port for forwarding the phone (though This is solved by re-crimping the telephone cable under RJ-45, because there is still one Passive Pass-Through port). The front PoE port gives the device connected to it no more than 8W. Due to the compact size, the antenna had to be soldered directly on the board, the gain is close to zero, as a result, the power (EIRP) turned out to be at 14dBm - 4 times less than generally accepted. In the end, you need a lot of points.

    In general and in general, one feels an orientation towards solid corporate installations in the office environment - in the same segment in which the NJ100 was positioned. Those who are “smaller and simpler” can be scared off by the need to purchase a controller even for installing 3-10 points, because they themselves do not work, and the inability to support STP on Ethernet ports (you need to invest in a full SCS). Non-offices (hotels / schools, etc.) definitely will not like the “sticking out in sight” RJ-45 ports, into which someone will definitely try to connect and the need to purchase a very large number of points.

    RuckusZoneFlex 7025 compares favorably with the lowest price, a very compact and competent design, support for 802.11n, the ability to purchase a "thin" or stand-alone version. Of the shortcomings - again, a low-power antenna and a protrusion on the back of about 4 cm - is insignificant when mounted in a box or in a recess in the wall (at the outlet), but you can’t mount the point on a flat surface. Ruckus Wireless is a popular choice for small organizations in the US and Europe (large ones need full manageability and great power) and knows how to please them. The main drawback is the limited presence in the CIS markets (up to a complete absence in some countries).

    Motorola(Solutions) AP-6511 entices users with increased signal power (one and a half times more than that of HP, for example) and MIMO 2x2 support, which should give significantly more coverage than competitors with a modular design (nozzles with different ports are available), different operating modes: autonomously, under the control of the controller. Best of all, the AP-6511 can act as a controller for 24 other points! In fact, Motorola (not particularly different from the HP approach) took the design achievements of the Tut Systems acquired in 2007, which has been working in the hotel industry since 1996 and knows what really works and what doesn't (and by the way, it invented HPNA), and “pinned” the point with its modern WiNG 5 platform - the same as in its “adult” line of points and controllers (which allows you to easily mix AP-6511 with other products on WiNG5 and expand the network).

    Among the shortcomings are dimensions, price (but because of more power, fewer points are needed, and a separate controller is not needed) and limited availability (not all CIS countries are certified). There is nothing surprising in the total superiority of Motorola's point - it came out last, and the company had the opportunity to look back at competitors, and even leave a reserve for the future. As I understand it, this is the next step in Motorola’s strategy of penetrating into Carpeted Space - offices, hotels, universities, where points of different form factors may be needed, and no one naturally wants to build several heterogeneous networks. (Historically, Motorola firmly seated in the retail and logistics - in the same place and its mobile computers)

    Total, a customer with SCS can now choose from two specialized solutions - HP (cheaper if it suits and especially good if LAN is also on HP) and Motorola (more expensive and more universal). Small businesses have an even cheaper Ruckus available (if you're lucky). Another popular option is to buy 12 “Cisco” points of the WRT or EA series, make 12 SSIDs (HOTEL-AP1 ... HOTEL-AP12), hang them on the line of sight and one above the other on the floors, and tune them all to one channel “to see each other ”(or on channels 1,2,3,4,5, .., 12). I saw both options more than once, it's a pity, only, the Internet does not work well :)

    And if there is no SCS?

    Those who do not have an Ethernet network and Cat5 wiring are invited to work according to what is available - over the telephone network. Solutions of this class are offered by Motorola (Private Broadband) and Teledex (ExpressNET AirLink). In both cases, the scheme is extremely simple - some client equipment (CPE) with DSL and Ethernet / Wi-Fi support (in fact, the VDSL bridge) is installed at the user connection point, and DSLAM is expanded on the PBX (PBX), the functionality of which is expanded in accordance with specifics of the solution (DHCP, Accounting, large fleet management CPE, QoS, etc.). It turns out a kind of corporate adaptation of the well-known ShPS, which was called Private Broadband (since it uses the organization’s own network, in contrast to public access networks). Essentially, regular VDSL. But not quite ordinary ...

    DSL technology solution scheme

    However, there is a specificity here. Factors previously insignificant come into play. First, cable infrastructure requirements. It is clear that DSL works well on Cat3, but not every DSL works well on a “noodle” basis. Especially if several lines pass nearby (crosstalk, etc.). I must say right away that both solutions will work poorly, the speed drops significantly. On the other hand, if the telephone network is in such a state that neighbors' conversations are heard in the handset, then it is unlikely that in this case the cordless phone is a priority issue on the agenda. The second significant nuance is the provision of food. If in the variant with Ethernet the points are powered by PoE, then the telephone network cannot provide 15W. So, either an additional 220B outlet is required (and it is not always there), or you will have to go to tricks. It is these two factors, plus the functionality of the DSLAM (in fact, the controller) that determine the functionality of the solution. Also, in this class of solutions, there is almost always a purely wired end equipment - the installation of access points in each room may be redundant, and Ethernet ports may be needed. Unfortunately, none of the solutions is available on the CIS market “off the shelf” - you need to contrive and import.

    First, consider the Teledex solution .. Everything is simple and beautiful here. Teledex has historically been a provider of telephones for hotels and institutions. We will integrate a VDSL bridge into the telephone, an Ethernet port - let's call it ExpressNET. We also integrate an access point into the phone - we get ExpressNET AirLink. Everything is logical and elegant - at one time this solution even received the award “Best New Technology Product 2004”. It is very convenient for those who are just expanding the network or thinking about its modernization. However, there are also disadvantages. Firstly, if the organization already has telephones, they will have to be installed somewhere, which is not very interesting in case of expensive system phones. Secondly, to power the access point, you still need a separate power supply (and a 220V socket), which are often not enough. Thirdly, the technology is out of date - access points do not interact with each other, do not work with the controller,

    Teledex ExpressNET AirLink is simple and elegant. An inquisitive reader who visits the site or reads a datasheet will notice that the phones are sold under the iPhone brand (since 2004!).

    Motorola's solution sets out the advanced DSLAM functionality, high DSL speed (up to 75Mbps) and, most importantly, the patented Adaptive Line Power technology - an analogue of PoE, but for a Cat3 cable with an effective range of up to 300m (600m for a purely wired solution). Obviously, in this case no additional power sources and 220V sockets are needed. This allows you to make subscriber equipment in the form of compact "blotches" on telephone sockets and, more importantly, install them almost anywhere, which makes this solution unique. This provides forwarding of the RJ-11 port for the "transparent" operation of telephony. In this case, DSLAM performs not only the role of an aggregator and an access node to Ethernet, but also a power source for points, a WLAN controller, an AAA server, and a QoS management system, providing a complete solution for the organization and operation of a multiservice network. Accordingly, the solution consists of a DSLAM that connects to the cross and provides power, and two types of CPE - MC-802 (Ethernet + Wi-Fi) and mT2 (Ethernet only). The solution itself went to Motorola with the acquisition of Tut Systems, so it has nothing to do with other Motorola wireless products, it has its own interface and does not integrate with them.

    Motorola MC-802 Wireless Wallplate, its mT2 wired fellow and T3 Hub Controller


    So to summarize. The growing popularity of wireless networks has led to the need for a new form factor of wireless equipment: from banal access points built into hotel telephones to elegant “outlets” with the functionality of a WLAN controller. At the same time, quite specific equipment is not expensive. On the contrary, it is possible to implement such a project with a budget two times smaller than what is required to build a “traditional” WLAN. The solution is interesting in that you do not need to lay SCS, if it is not there, it is enough to have a telephone network with a PBX to get both a wireless network and a wired network "in load". For domestic hotels, this, in fact, makes it possible to instantly jump from today's realities to the level of providing Internet access (wired and wireless), PayTV, IP-telephony, providing infrastructure for video surveillance and much more - without the need to pull the cable and affect the interior. It’s enough to deploy PowerBroadband class solutions and connect it to the billing system. If there is SCS, offices of any scale can quickly and relatively inexpensively deploy full-fledged high-speed Wi-Fi 802.11n, which can be easily reconfigured during redevelopment or picked up when moving - regardless of whether they are in a business center or in a historic building with meter the walls. And if in a historical building it is forbidden even to carry out construction work (to lay SCS) - again solutions on DSL will help out. The network is easily expandable and managed by untrained users. It seems to me that such a combination of price, simplicity and convenience should be very much in demand in the conditions of our realities.

    PS Well, and if there is no wiring at all - you can always build a Wi-Fi Mesh, and connect a point or controller via a 3G modem. Fortunately, the 5GHz band is already allowed inside buildings, and there are a lot of normal equipment that can build Mesh in the same 2.4GHz band. True, the organization Mesh is a separate big topic with its own nuances, pitfalls and marketing omissions of manufacturers.

    PS The article was previously published (by me) on the Computer Review website , but I think it will be of interest to the general public. If anyone knows how to put this on the Motorola blog, I will be grateful. It looks like the blog has died ...

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