Cisco Aironet Series 1850 Access Point Deployment Guide
Cisco Aironet Series 1850 Access Point Deployment Guide
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ContentsChannel Rail
Adapters – Cisco Part Number AIR-CHNL-ADAPTER
When mounting APs to
ceiling channel rails, an optional channel adapter AIR-CHNL-ADAPTER is used.
The channel adapter comes in a two-pack and is attached to the ceiling grid
Figure 1. Example of
Channel Rails
Figure 2. AIR-CHNL-ADAPTER
(left) Slides Onto the Rails
Figure 3. AIR-CHNL-ADAPTER
Mounted to Rail Clip (left) and Finished Installation (right)
Contents Physical Hardware
and Mounting Options of an AP
Figure 4. AP 1850 Model
Ports are easily
accessible. Mode button is recessed and requires a tool such as a paperclip to
Note the vent holes
below the ports, avoid using chemicals or solvents around the AP as the ingress
of such materials have the potential to cause damage to the device.
AP 1850 has similar
physical dimensions as other Cisco APs but with a few differences in physical
appearance, most of which are cosmetic changes to distinguish the different
models. The mounting options and bracket configurations are identical and
interchangeable between Cisco , , , and 3700
series APs.
Figure 5. Mechanical
Dimensions AP 1850
Figure 6. Mechanical
Dimensions AP 1850
Different installation
options are available depending upon the requirements of the customer. Brackets
are available from Cisco as well as third-party companies. During the ordering
process, the customer may choose one of two brackets (but not both). Each
bracket is a zero-dollar ($0) option at the time of configuration. If the
customer does not choose a bracket, the selection default is AIR-AP-BRACKET-1,
which is the most popular for ceiling installations. The other choice is a
universal bracket that carries part number AIR-AP-BRACKET-2.
Figure 7. Access Point
Bracket Choices
If the AP needs to be
mounted directly to a ceiling on the grid work, then AIR-AP-BRACKET-1 is flush
mounted and has the lowest profile. However, if the AP is mounted to an
electrical box, other wiring fixture, inside a NEMA enclosure, or wall mounted,
then AIR-AP-BRACKET-2 is a better choice. The extra space in the bracket allows
for wiring, and the extra holes line up with many popular electrical boxes.
When mounting the bracket to the ceiling grid work, some ceiling tiles are
recessed. For this reason, two different styles of ceiling clips, such as
recessed and flush rails are available
Figure 8. Different Clips
are Available for Attaching to Ceiling Grid Work
ContentsWall Mounting the
When the AP needs to
be wall-mounted, the installer should understand that walls can be a physical
obstacle to the wireless signal. Therefore, maintaining 360 degree coverage may
be compromised by the wall. If the wall is an outside wall and/or the goal is
to send the signal in an 180-degree pattern instead, a directional antenna,
often referred to as a “patch” antenna, may be a better choice assuming that
the AP 1850e is used.
Avoid wall-mounting
APs with internal antennas, such as the AP 1850i, unless you use the optional
Oberon right-angle mount ().
The internal antenna model is designed to mount to a ceiling to provide
360-degree coverage. If wall-mounted in a non-ceiling orientation, the signal
may penetrate the floor above and below causing unintended coverage. This
results in additional and needless roaming access when a mobility client, for
example a user with Wi-Fi phone, walks by on an adjacent floor.
Instead, use the AP
1850e (with dipoles or patch antennas) or use an optional wall mount that puts
the AP 1850i or AP 1850e into a ceiling type orientation when mounted to a
APs with internal
antennas such as the AP 1850i that are wall mounted should use the Oberon
mounting bracket unless roaming is not an issue, for example, hotspot, kiosk,
or small venue scenario.
Figure 9. Wall-Mounting
APs Antennas Should be Vertical (Up/Down) or Use the Oberon Right-Angle
Mounting Structure - Ideal for the “I” series such as 1850i, 2700i, 3600i or
3700i Oberon P/N 1029-00)
Oberon model 1029-00
is a right angle mount works with “i” and “e” models to put the AP in the right
antenna orientation. If the unit is an “e” model with dipoles that can be
mounted (far right), then an Oberon wedge mount is not required.
ContentsAbove the Ceiling
The AP 1850 series is
rated for installation in the Plenum area (UL-2043). Many customers prefer to
locate the AP in such a way that nothing is visible on the ceiling. In some
cases, this is preferred for aesthetic reasons, so customers may install the AP
above a drop ceiling. This may also be preferred in high theft areas such as
classrooms or in areas where policy dictates that nothing can be visible on the
To meet this hard
requirement, optional T-Bar hangar accessories such as Erico and Cooper, can be
These accessories are manufactured by third-party companies. The Erico Caddy
512a, the Cooper B-Line BA50a, or similar T-Bar Grid T-Bar hangars can be used.
For more information,
Figure 10. Example of How
to Hang an AP Above the Ceiling Tiles
Installing APs above
the ceiling tiles must be done only when mounting below the ceiling is not an
option. The tiles mu such installations will degrade
advanced RF features such as voice and location, so verify coverage and
performance. Always, try to mount the AP as close to the inside middle of the
tile as possible, and avoid areas with obstructions
Figure 11. Installing AP
above ceiling tiles: Pick an area Clear of Obstructions and Avoid Ceiling
ContentsStadium / Harsh
Environments
Customers needing to
install the APs in harsh environment such as sporting areas, stadiums, open
garden areas, or warehouse freezers, where it may be exposed to weather, may
use a NEMA type enclosure.
Some APs may not be
certified for outdoor deployments in a NEMA enclosure. This varies around the
world, for example some regulatory agencies permit AP outdoor NEMA enclosures
if the AP is indoors such as a freezer or garden area but may prohibit its
usage outdoors. This seems to vary with regard to weather radar compliance,
UNII-1 compliance, and so on. Check with your Cisco account team or the
communications regulatory agency that has jurisdiction in your area.
Figure 12. Example of NEMA
16x14x8 Enclosure with Pressure Vent on Bottom
Third-party sources
for NEMA type enclosures include:
When using a NEMA type
enclosure, ensure that the cables exit out of the bottom of the enclosure so
that rain and moisture do not run down the cable into the enclosure. Also, the
color of the enclosure may af for example, a black
enclosure gets much hotter in the sun than a white one. You may also want to
use a pressure vent to prevent moisture accumulation.
ContentsEthernet Cable
Recommendation
While the AP , ,
and 3600 work fine with CAT-5e cable, for newer cable installations, it is
recommended that the customers use CAT6a. Because, CAT6a is the cabling
required by the 10GE standard.
ContentsAntenna Cable
Recommendation
practical/possible, ensure that the antenna cable runs as short as possible.
Cisco offers low loss (LL) and ultra low loss (ULL) cables, which have the same
characteristics as Times Microwave LMR-400 and LMR-600.
Cisco cables carry the
part number AIR-CAB (Aironet Cable) and its length parameter. For example, a 20
Ft length of LL cable with RP-TNC connector is Cisco AIR-CAB-020LL-R. These
heavy black cables are not Plenum rated and are primarily for outdoor use or
manufacturing areas.
Figure 13. When Drilling
Holes for Cable, Allow for Size of Connector (Typically 5/8 Inch) Drill
ContentsAccess Point Spacing
Recommendations
If you have an Wi-Fi
device such as an AP and you are going to use another AP in the vicinity on a
different channel, it is recommended that you space each AP apart by
approximately 6 ft (2 meters). Avoid clustering the APs or the antennas from
different APs together, because this could cause degradation in performance.
This recommended distance is based on the assumption that both devices operate
in the unlicensed band and do not transmit RF energy more than 23 dB, that is,
200 mW. If higher power is used, space the APs farther apart.
If you have other
devices that transmit, especially if they operate in the same frequency ranges,
for example, frequency hopping legacy APs or other devices that operate close
in frequency to those of the AP (think below or above the 2.4 and 5 GHz band),
you should consider moving or separating the devices as far as you can. After
you have done this, check for interference by testing both devices at the same
time under heavy utilization (load) and then characterize each system
independently to see how much, if any, degradation exists.
To comply with FCC,
EU, and EFTA RF exposure limits, antennas should be located at a minimum of 7.9
inches (20 cm) or more from the body of all persons. For more information, see
the Declarations of Conformity section in the
ContentsInstallations in IDF
Closets (Telecommunications or Other Electrical Equipment)
When installing APs
near electrical or telecommunications equipment, keep all wiring and metal away
from the antennas and avoid placing the antennas near electrical lines. Do not
route wiring electrical or Ethernet in the near field (6-15 inches) from the
antenna. Try to refrain from installing the AP in the electrical closet,
because the best place for the AP is as close to users as possible/practical.
If you have remote antenna cables from such a closet, you may be required to
use Plenum rated cable (see local fire/safety regulations for more on this).
Below are a few URLs
for understanding interference:
ContentsInstallations Inside
and Around Elevators
Elevator coverage can
sometimes be accomplished by placing APs in the near field of an elevator,
typically on each floor near the elevator door. Because, elevators often have
metal doors and the shafts are often concrete or contain other materials that
degrade Wi-Fi coverage. It is important to check the coverage inside the
elevator. Though such coverage can be challenging, it is often do-able,
especially if the elevator is only a few floors.
High rise elevators
are more challenging because roaming is the client is
cycling through a large number of APs quickly. Some companies that do
in-elevator advertising put a patch antenna on the floor inside the shaft and a
patch antenna on the bottom of the elevator car, while other companies use
leaky coaxial cable running on the side of the shaft.
When installing any
Wi-Fi equipment inside the elevator cars or shafts, local regulations need to
be followed. Because, many times such installations are prohibited either for
safety reasons or because the building owner or local fire department may
prohibit the same. Only elevator repair persons or contractors who have
experience with this kind of work should be in those areas.
Contents Understanding AP
1850 Powering Options
Figure 14. Local 48 Volt DC
Power Supply
ContentsPoE
Negotiation
When the AP negotiates
802.3at (high power), it always tries first to negotiate using Cisco Discovery
Protocol (CDP). If the negotiation fails, the AP will attempt to negotiate
using Link Layer Discovery Protocol (LLDP). LLDP is a vendor-neutral method for
advertising device identity and capabilities.
So, the AP 1850 first
uses CDP to get 20.9 W and reserve that amount of power. If CDP fails, the same
process starts using LLDP. So, a non CDP response time out (often approaching
60 seconds) would need to occur before the LLDP negotiation starts. In both
cases, the requirement is obtain 20.9 W power.
If the AP has enough
power, it shows Full Power in the PoE settings. See
Figure 15. Power over
Ethernet showing Full Power Mode
However, if the power
source equipment such as PoE switch, mid-span, or injector lacks the ability to
properly negotiate high power, go to “ANY” mode and take whatever power the
device can provide, which would likely be 15.4 W (802.3af).
If the power source is
limited to 15.4 W (802.3af), then the AP negotiates and reserves 15.4 W.
The AP functions with
the available power sourcing. If the power is not enough to be fully
functional, then the AP makes an effort to shut down and re-negotiate to be
able to function at 15.4W. Also, the AP indicates LOW or MEDIUM power on the
controller and functions at reduced capability. See
If the power source
does not support Cisco Discovery Protocol, for example third party switch, then
uncheck its usage. See
Table 1 Power over
Ethernet options
Power Budget
Capability
This is the CDP/LLDP value that we ask in software, switch
pads another 2 - 3 W for cable loss at 100 m.
ContentsApproved antennas
and Radiation Patterns
Figure 16. Picture of the
internal antennas within the AP 1850
The internal antennas
are rated at 3 dBi at 2.4 GHz and 5 dBi at 5 GHz.
Figure 17. Radiation
pattern at 2.4 GHz
Figure 18. Radiation
pattern at 5 GHz
Antennas for Outdoor
Deployments
The AP 1850 is
designed for indoor deployments. However, using a NEMA enclosure or mounting
the antenna outdoors may be acceptable (depending upon your location as some
countries do not permit this).
In the U.S.,
installers who need to deploy APs outdoors are recommended to use the “P”
series products such as the Cisco Aironet AP 3600P and AP 3700P. For more
information, See the
All Cisco antenna
connectors are labeled as “A,” “B,” “C,” and so on. “A” has a higher priority
than “B” or “C/D”. So, if the AP supports, for example 3 or 4 antennas and you
only have 2 antennas, you can use them on ports “A” and “B” for a short period
until you install the additional antennas provided you turn off the unused
antenna ports on the controller or AP software.
While it is not
recommended to use less antennas, the product (in a pinch) supports 802.11a/b/g
clients or single spatial stream .11n clients using only one or two antennas.
However, there is a significant performance hit and you will also lose
ClientLink functionality. If you do this, you will also have to configure the
AP in the software to not use the other antenna. Failure to do so could result
in performance issues.
The following Dual
Radiating Element (Dual-Band) antennas are approved for use with the AP 1850e
series access point:
AIR-ANT2524DB-R=
Dipole Black 2dBi @ 2.4 GHz – 4dBi @ 5 GHz
AIR-ANT2524DG-R=
Dipole Gray 2dBi @ 2.4 GHz – 4dBi @ 5 GHz
AIR-ANT2524DW-R=
Dipole White 2dBi @ 2.4 GHz – 4dBi @ 5 GHz
AIR-ANT2535SDW-R=
Short Dipole 3dBi @ 2.4 GHz – 5dBi @ 5 GHz
AIR-ANT2524V4C-R=
MIMO Omni Ceiling 2dBi @ 2.4 GHz – 4dBi @ 5 GHz
AIR-ANT2566P4W-R=
MIMO Patch 6dBi in both bands
AIR-ANT2544V4M-R=
MIMO Wall Mount Omni 4dBi in both bands
AIR-ANT2566D4M-R=
Medium Ceiling / Auditorium Patch 6dBi in both bands
For additional
information on Cisco antennas, see
The antenna reference
guide has details of all Cisco antennas. You can also find individual data
Always use Cisco
antennas whenever possible. See
Cisco has also
introduced a new smaller size dipole. While this antenna does not have an
articulating knuckle, it is much smaller in size and is a good choice when
aesthetics is a primary concern.
shows an AP-3700 with both types of dipoles.
Figure 19. Standard Dipoles
and Short Dipoles (On Right)
Figure 20. Radiation
Pattern for the Short Dipole AIR-ANT2535SDW-R
In addition, the
antennas below may also be used with , , and 3700 “e”
Series APs.
Figure 21. Specifications
for the AIR-ANT2524Dx-R Dual-Band Dipole Antenna
Figure 22. Radiation
Pattern for the AIR-ANT2524Dx-R Dual-Band Dipole Antenna
Figure 23. Specifications
for the AIR-ANT2566P4W-R Dual-Band Patch Antenna
Figure 24. Radiation
Pattern for the AIR-ANT2566P4W-R Dual-Band Patch Antenna
Assuming that the
antenna is mounted on a wall, the Azimuth (in Red) is the signal going forward
from the antenna. The elevation, in Blue, is the “up/down” pattern.
Figure 25. Specifications
for the AIR-ANT2524V4C-R Dual-Band Omni Antenna
Figure 26. Radiation
Pattern for the AIR-ANT2524V4C-R Dual-Band Omni Antenna
Figure 27. Specifications
for the AIR-ANT2544V4M-R Dual-Band Omni Antenna
Figure 28. Radiation
Patterns for the AIR-ANT2544V4M-R Dual-Band Omni Antenna
For a granular
pattern, see the individual specification sheet of the respective antennas.
ContentsGeneral
Considerations – WLAN Best Practice Guidelines
Following are some
guidelines to remember regarding AP deployments:
Always try to
mount the AP as close to the users as possible for best performance. Be aware
for example, hospitals have metal doors and coverage can
change when the doors close. Old buildings can have metal grid work in the
plaster or asbestos. Avoid mounting the AP or antennas near metal objects, as
doing so can change the coverage area.
When using the 2.4
GHz frequency, the same 1, 6, and 11 channel scheme is used as the 5 GHz
channel scheme ().
Avoid putting all the APs on the same channel, and reuse channels as you can.
See other deployment guides for more on this topic.
Figure 29. Example of
Channel Usage in 2.4 and 5 GHz (Two Channels used if 40 MHz)
Try to determine
which clients are going to be used and check the coverage using those clients.
For example, a PDA or Wi-Fi phone might not have the same range as a notebook
or tablet.
Verify coverage
using the worst performing clients that you intend to deploy.
The Cisco AP 1850
series supports standards based transmit beamforming and is positioned for
newer Wave-2 MU-MIMO and 4-SS clients. The Cisco 2700 and 3700 series APs with
ClientLink 3.0 will perform better than the AP 1850 when using legacy .11g/n
and .11ac Wave-1 clients. This is because the performance improvements with the
AP 1850 are designed to take advantage of 4-SS and Multi-User MIMO (Wave-2
clients) and does not support Cisco’s enhanced Client Link beamforming for
legacy clients.
While site surveys
are generally recommended, if the design is done at half power and Cisco RRM is
in place, sometimes a limited site survey (coverage check) is adequate for
smaller venues. If it is a very challenging environment such as train
connectivity, Gas & Oil verticals, large hospitals, and so on, Cisco has an
Advanced Services team that can be contracted to help you get up to speed or
perform your installation. Contact your Cisco account team for more
information.
The rule of thumb
coverage plan is 1 AP per 5,000 square feet for data and 1 per 2,500 square
feet for voice and location services, which roughly means 1 AP per 50 feet for
best performance.
Try to leverage 5
GHz for more and cleaner channels / spectrum.
Try to create 10 –
20% cell overlap for optimized roaming and location calculations /
transactions.
Consider separate
SSIDs for Corporate and Guest Access with Guest being Rate Limited.
Enable band
steering, so that the dual band clients are motivated to use 5 GHz to avoid
slower 2.4 GHz channels.
Use Category 5E or
better for Gigabit Ethernet or mGig.
Some clients
(especially older ones) do not support the UNII-2 extended client channels 100
– 140. So, if you have lots of older clients, you may need to disable them in
the DCA channel list.
Clients with later
chipsets (especially later 802.11ac clients) should support extended UNII-2
The following lists
the Wi-Fi signal strength guidelines:
-65 to -67 = Data,
Voice, Video, Location, High Density
1 access point
per 2,500 square feet / every 50 feet
-68 to -69 = Data,
Voice, Multicast and Unicast Video, Location
-70 to -71 = Data,
Unicast Video
-72 or greater =
Contents802.11ac Wave-2
primer and the AP 1850
For an overview of 802.11ac, see the
technical white paper at the following URL:
Key differences with 802.11ac Wave-2 using the AP 1850 are:
The ability to use 1, 2, 3 (and now 4) Spatial Streams
An extra Spatial Stream gives you a bump in data rate @ 80 MHz 1733
versus1300 Mbps
Same channel bonding 20, 40, 80 (does not support 160 MHz)
11ac Beamforming (was in Wave-1) now implemented, but only 11ac
clients participate in .11ac beamforming
Multi-User MIMO (MU-MIMO) support—supported in Wave-2 for 11ac Wave
2 clients only
Based on IEEE 802.11ac final standard—ratified Dec’2013
Clients Supporting 3
and 4 Spatial Streams
Clients with 3SS
support are starting to become a commonplace with 4SS and MU-MIMO Wave-2
clients on the horizon. As the new 802.11ac specification starts to get
traction, many newer client adapters will have more advanced chipsets and
support 3SS and 4SS as a subset to 802.11ac. Additionally, the Cisco AP 1850
fully supports all the DFS frequencies for more usable channels in the 5 GHz
range. More clients, especially 802.11ac clients, will start supporting these
newer channels in legacy 802.11n modes as well.
Currently, the most
popular 3SS client is the Apple 2011 MacBook Pro, because it is based upon the
Broadcom BCM4331 chipset and a small USB adapter by Trendnet, that is, TEW
684UB, based on the Ralink chipset.
Additionally, the
Intel 5300 and 6300 modules have supported 3SS for a long time. Because of the
different types of notebooks that these cards are installed in, testers have
observed good throughput on many notebooks (+320 Mbps) and reduced throughput
on other notebooks such as 240 Mbps. If you experience low throughput using the
Intel card, you may try a MacBook Pro or Trendnet adapter. If they perform
well, try another notebook with the Intel card or open a case with Intel or the
laptop manufacturer for a possible remedy. During the AP 3600 beta trials,
Cisco observed differences in performance with different notebooks using the
Intel 6300 card.
Sometimes, it can be
difficult to reliably maintain a 3SS link because it is easy for the client to
rate-shift out of the 3SS mode. The client plays an important role in the
ability to maintain a 3SS link, so it can vary with the quality of the client
being used and the test environment.
ContentsUnderstanding
Channel Plans and Bonded Channels
Currently in the US,
there are 25 (20 MHz) channels, 12 (40 MHz) channels, and 6 (80 MHz) channels.
802.11ac (Wave-2) supports 160 MHz channels but currently there are only two
channels available. This is likely to get better, because the Federal
Communications Commission and other regulatory bodies realize the need for more
unlicensed spectrum and are actively working to free up more spectrum.
Let us take a look at
the frequencies available and how the channel bonding would work.
Right now in the US,
there are only four 80 MHz channels but this is likely to improve.
Figure 30. Current Channel
Allocation Plan - US Theater
Figure 31. Current Channel
Allocation Plan - ETSI Theater
spectrum allocation?
In the US, there
are currently 25/12/6/2 channels with bandwidth 20/40/80/160 MHz channels.
With the opening
up of 5.35 – 5.47 GHz and 5.85 – 5.925 GHz, the number of channels increases to
34/16/8/3.
If the industry
manages to take back the TDWR channels, the number increases to 37/18/9/4.
So, as time
progresses, you should see additional channels becoming available.
Figure 32. Proposed
Channel Plan for US Theater (Not Fully Committed as of this
deployments and surveys are not much different than 802.11n deployments.
supports faster 256 QAM modulation allowing 802.11ac clients the ability to use
faster and a wider range of data rates, thus permitting clients to maintain
higher connectivity rates.
When deploying 80 MHz bonded
channels, ensure that you have enough spectrum for 80 MHz channels. Note that
this can be a major change to your existing spectrum plan.
ContentsUnderstanding
Channels and How They Relate to the Client
Most clients (USB)
that are emerging are 2 spatial stream, and by using 80 MHz bonding, you can
achieve up to 866 Mbps.
shows the Netgear A6200 client card.
Figure 33. Example of a
2-ss Client Bonded at 80 MHz
The software reports
channel is 36 (this is where the channel bonding starts). On a spectrum
analyzer, you can see that the actual channels in use are 36, 40, 44, and 48.
Figure 34. Example of a
Bonded 80 MHz Channel
For clients to link
at 80 MHz, you have to set the channel width to 80 MHz on the AP.
Figure 35. Setting an AP
1850 to an 80 MHz Channel from the Controller.
Contents802.11ac and Legacy
Client Recommendations
Devices such as
Samsung Galaxy S4, ZTE’s Grand Memo, HTC One, and new notebooks such as the
Apple 2013 Macbook Pro are the first to market 802.11ac devices. It is expected
that integrated notebooks and tablets (those devices often supporting 2 and 3
spatial streams) will start to become a commonplace.
Currently, Cisco’s
test bed for interoperability has the following configuration types.
Table 2 Interoperability
Hardware/Software Parameter
Hardware/Software Configurations Type
Interoperability
matrix for APs, Clients and security types tested with the below clients.
Table 3 Laptops and
Clients Tested for Interoperability
Client Type
Table 4 Hand Held
Devices Tested for Interoperability
Table 5 Phones and
Printers Tested for Interoperability
Phones and
Contents802.11ac Devices on
the Market
Integrated Devices – Shipping
Apple - Macbook Air
Intel Dual Band Wireless - AC 7260
Samsung S4
ZTE Grand Memo
USB Clients - Shipping
LinkSys AE
Asus – USB-AC53 2x2
NetGear – A
Belkin P-F9L1106 - 2x2
D-Link DWA-182 – 2x2
Buffalo ac866 – 2x2
Edimax EW-7822AC– 2x2
Ethernet to 802.11ac Bridges - Shipping
LinkSys (Belkin) WUMC710
Buffalo WLI-H4-D1300
List for identifying new 802.11ac hardware:
ContentsVariables Impacting
Performance
Some early
observations show that USB clients can appear to be a bit slow in performance
depending on drivers, USB port versions, and so on. Also, it is observed that
some clients have trouble in maintaining an 80 MHz bandwidth in the Dynamic
Frequency Selection (DFS) bands.
lists the clients that had reasonable success during testing.
Table 6 List of 802.11ac
Clients and Driver Versions
Wi-Fi is a highly
variable technology and there are many factors that could impact performance.
Few examples are: environment, client, channel, AP placement, and client
distance from the AP.
spectrum clean?
If you are not
seeing the results you expect, you need to first check the coexistence with
other Wi-Fi networks. Also, you need to ensure the entire 80 MHz wide channel
or whatever you have bonded together is clear. The easiest way to confirm this
is to put your
into SE Connect mode and have a look on Spectrum
Expert or Metageek Chanalyzer Pro. This will allow you to see Wi-Fi and
non-Wi-Fi interference on all channels.
What client
are you using?
The client will
have a big impact on performance. First, you need to check if the client is 1,
2, or 3 spatial stream? Then, check the interface used? A USB 3.0 client
performs much better than a USB 2.0 client. Integrated radios are the best of
all, because they can take advantage of a fast bus speed as well as the
built-in antennas of the device. So, it is recommended to use devices such as
the Samsung Galaxy s4 (1x1) or the Apple MacBook Air (2x2) over USB clients. We
certainly recommend USB 3.0 products over USB 2.0 products.
What channel
are you using?
If you are doing a
Rate versus Range demo, it is important to choose your channel carefully.
Obviously, you need to ensure that the channel is clear. However, not all
channels are created equal. Some channels have total output power restrictions.
So, Cisco recommends UNII-3 or UNII-2, over UNII-1 for best performance.
How far is the
client from the access point?
Check how far is
the client from the AP. 802.11ac introduces 256 QAM, which is a more complex
modulation. So, the modulation is harder to maintain over distance. If you want
to consistently show 256 QAM, which equates to m8 and m9, it is recommended to
keep the client within 25’. Beyond 25’, you will still see m8/m9, but not
consistently.
Keep in mind, m7
is the same for 11n and 11ac, the difference being, 11ac allows for 80 MHz
channels. Under ideal conditions, you can expect 11ac to have an almost 3x gain
over 11n at m9 and a 2x gain at m7.
How is the AP
AP placement needs
to be considered. For close-in tests, less than 10’, placement is not so
important. Just make sure that the AP is not obstructed. For other tests, you
must take care to mount the AP in a proper location (ceiling or high on a wall
in the right orientation).
Try to follow
these best practices: avoid mounting the AP near metal, mount it horizontally
on a ceiling, and so on.
What data rate
is the AP transmitting to the client at?
It is often useful
to monitor the data rate of the client. The data rate has a direct impact on
performance. There are several ways to monitor the data rate. The easiest
method is to check on the GUI.
ContentsA Quick Look at a
Few Non-Optimal Installations
This section lists
some examples of installations that are not recommended. It is very difficult
to provide good Wi-Fi service with a poor installation. Always try to avoid
metal and clutter.
Figure 36. Example of an AP
Installation Near Metal and Clutter (Try to Avoid Metal and
Figure 37. Patch Antenna
Against a Metal Fence
Figure 38. Example of an AP
Installation Near Metal and Clutter (Try to Avoid Metal and
Figure 39. Example of a
Poor Installation - Access Point Needs to be Level and Not Swing or Move
When mounting devices,
the AP should be level and secured so that it does not sway or move. Keep the
AP away from metal objects and try to place it as close to the users as
Figure 40. Example of a
Poor Installation – Access Point is too High and Buried in Conductive
Remember, the best
place for an AP is as close to the users as possible. Avoid metal or conductive
objects in the near field (they cause the radio waves to become directional and
increases nulls (dead spots)). If you must mount the AP in a high ceiling, look
at directional antennas to direct (angle down) the signal to the intended
target area and always mount dipoles in the correct orientation.
Figure 41. When Using
Dipole Antennas Observe the Correct Orientation (Vertical
When mounting
antennas outside, always mount with the WIRES DOWN and never obstruct or put
weather proofing material over the drain holes.
Figure 42. Always Mount
Antennas Outdoors with Leads DOWN (Indoors Does not Matter)
Figure 43. If Antenna
Connectors are Exposed to Weather – Coax-Seal Should be Used but if Present, Do
Not Cover Antenna Drain Holes
Contents New
Auxiliary Ethernet
AP 1850 has an
additional Ethernet port labeled "AUX", that is, Auxiliary port used for LAG
connection to the Ethernet switch supporting LAGB or for downstream traffic.
The Ethernet uplink port to the controller on the AP 1850 is labeled "PoE".
Link Aggregation
for the AP 1850
Many Ethernet switches
support links up to 1 Gbps throughput. However, with newer Wave-2 access points
such as the AP 1850, it is possible (or at least the potential exists) that the
AP traffic could exceed 1 Gbps. It is not likely to occur until MU-MIMO and 4
spatial stream Wave-2 clients become more commonplace.
To address this
potential issue, we have implemented Link Aggregation into the Cisco AP 1850.
Link Aggregation is
the only method to gain higher throughput on AP 1850 as it does not support
multi-gigabit technologies such as NBase-T.
For more on
multigigabit technology, see the following URL:
It is expected that
future Wave-2 access points may support multigigabit functionality.
Cisco Switches
Supporting Link Aggregation
The following Cisco switching series support LAG with the AP 1850:
Catalyst 3850 / all models (non-CA mode)
Catalyst 3650 / all models (non-CA mode)
Catalyst 4500/Sub-8E
Enabling link
aggregation on the AP 1850
ProcedureStep 1
Enable the
controller to support LAG for all APs using the command:
ap lag-mode support enable
This will NOT
result in a reset and reboot of the APs that support LAG.
To disable the
LAG on all APs, use the command:
config ap lag-mode support
This will result
in a reset and reboot of all the APs that support LAG.
Enable LAG mode
on the individual AP 1850 using the command:
config ap lag-mode support
&ap-name& enable
To disable the
LAG on the AP, use the command:
ap lag-mode support &ap-name& disable
support LAG will reset and will reboot only if the LAG state is toggled between
enable and disable.
For optimal
traffic load balancing on the LAG ports to the AP and the controller, it is
important that the switch support balancing is based purely on the L4 source
and destination ports.
configuration on the Cisco 3850 switch is shown below, where the AP 1850 is
connected to G6/0/13 and G6/0/3 on the wired0(plink) and wired1 (Aux port)
respectively.
port-channel load-balance src-dst-port
interface Port-channel1
description To AP-1850
switchport access vlan 192
switchport mode access
interface GigabitEthernet6/0/3
switchport access vlan 192
switchport mode access
channel-group 1 mode active
interface GigabitEthernet6/0/13
switchport access vlan 192
switchport mode access
channel-group 1 mode active
The state of
the LAG configuration on the controller and AP can be seen using the following
commands on the controller:
show ap lag-mode
show ap config general
The successful
formation of LAG between AP and the switch can be seen using the following
commands on the switch:
lacp internal
Downstream Device
connection for the AP 1850
The AUX port is designed to function as a downstream port. The AUX port
is ideal for devices such as video cameras, projectors, IP Phones, Point of
Sale terminals, and other end point devices. Also, it is designed to perform
port Link Aggregation (LAG).
Additionally, this AUX port will be disabled if the AP is powered by a
limited 15.4 W .3af PoE source because it requires PoE+, .3at, or local power
(wall brick type power supply) to properly function.
The AUX port is not manageable and is simply bridged back to the
controller. Avoid connecting another AP to this port or devices such as
switches/hubs or the same switch or uplink as the PoE port because it can
create spanning tree loop issues.
For example, if you configure the switch port (to AP 1850) as access in
VLAN 5, then the traffic comes from the AUX port.
If you configure the switch port to trunk, the AP 1850 will be in the
native VLAN and the AUX port will also be in native by default. Traffic from
the AUX port will not be sent to the WLC, and the AP 1850's built-in switch
will drop the traffic in the native VLAN.
This feature will not be implemented on the initial release of the
code. The initial release will only support LAG.
The USB port is not enabled in the
first release of this software. This will be enabled in the later release.
ContentsUnderstanding
Multi-User MIMO
With 802.11n, a device
can transmit multiple spatial streams at once, but only directed to a single
address. For individually addressed frames, only a single device (or user) gets
data at a time. This is referred to as Single-User MIMO (SU-MIMO). With the
advent of 802.11ac Wave-2, a new technology is defined, called Multi-User MIMO
(MU-MIMO). Using this technology, an AP can use its antennas and radio systems
to transmit to different clients, all at the same time over the same frequency
Figure 44. Example of
Figure 45. Example of
MU-MIMO with the AP
1850 is limited to a maximum of 3 spatial streams simultaneously.
To send data to user
1, the AP forms a strong beam towards user 1, shown as the top right lobe of
the blue curve ().
At the same time the AP minimizes the energy for user 1 in the direction of
user 2 and user 3. This is called “null steering” and is shown as the blue
notches. In addition, when the AP sends data to user 2, it forms a beam towards
user 2, and forms notches (nulls) towards users 1 and 3, as shown by the red
curve. The yellow curve shows a similar beam towards user 3 and nulls towards
users 1 and 2. In this way, each of users 1, 2, and 3 receives a strong copy of
the desired data that is only slightly degraded by interference from data for
the other users.
Figure 46. MU- MIMO Using a
Combination of Beamforming and Null Steering to Multiple Clients in
For all this to work
properly, especially the deep nulls, the AP has to know the wireless channel
from itself to all of the users very accurately. Because the channel changes
over time, the AP has to keep measuring the channel, which adds overhead.
Meanwhile, the client
receives its desired signal distorted by some interference from the signals
intended for other users. This interference makes the highest constellations
such as 256QAM infeasible within an MU-MIMO transmission.
In summary, MU-MIMO
allows an AP to deliver appreciably more data to its associated clients,
especially for small form-factor clients (often BYOD clients) that are limited
to a single antenna. If the AP transmits to two or three clients, the effective
speed increase varies from a factor of unity (no speed increase) up to a factor
of two or three times, according to wireless channel conditions.
You cannot configure
to use MU-MIMO, the clients will advertise this capability and the AP will put
them into groups.
Elements of
Multi-User MIMO
802.11ac MU-MIMO
is similar to traditional 802.11n MIMO, except instead of one client at a time,
it supports up to several clients that can all receive different data
simultaneously.
pre-coding basically aggregating clients that advertise
MU-MIMO capability into groups that participate in MU-MIMO process.
elaborate process. In MU pre-coding, when the AP is beamforming the signal, for
example at 1SS or 2SS rate to a particular client, the space-time streams have
to be constructed so that it also simultaneously null-steers to those
space-time streams being sent to the other clients.
All users’ MPDUs
are padded to the same number of OFDM symbols. The AP seeks out opportunities
to send similar size packets out to the MU-MIMO clients to optimize on air time
increasing throughput by sending data out to 2 – 4 clients per transmission.
The number of clients depends on the type of stream, for example one client can
receive 1SS while another is receiving 2SS.
Wi-Fi alliance
certification for Wave-2 includes MU-MIMO.
Take-away:
MU-MIMO is designed to maximize downlink capacity by overlapping clients in
space (multiplexing). Best performance occurs with high client counts and high
AP densities.
Challenges of
Multi-User MIMO
Requires precise
(CSI) channel state information to maintain deep nulls so that each MU-MIMO
client can properly decode its data without too much interference from the
other clients.
MU-MIMO CSI,
pre-coding group data adds overhead as does their acknowledgments and so on.
Rate adaptation
is slow – Wave-2 clients to be integrated into new laptops, tablets, and phones
but this moves slowly.
MU-MIMO is a new
technology and needs to develop and mature. So, issues such as lower end
clients may be sensitive to MU grouping overhead and client driver version
Figure 47. Example of a
MU-MIMO protocol advertisement
ContentsChecking the Access
Point LEDs
Access Point Status
Regarding LED status
colors, it is expected that there will be small variations in color intensity
and hue from unit to unit. This is within the normal range of the LED
manufacturer’s specifications and is not a defect.
The access point
status LED indicates various conditions and are described in
Table 7 LED Status
Indications
Message Type
Status LED
Ethernet Port
Each Ethernet port has two LEDs for
showing Link (Green) and Activity (Amber) statuses. They are integrated on the
RJ45 connector. For a description of the statuses they indicate, see the
following table.
10M Active
100M Active
1000M Link
1000M Active
ContentsQ & A
Q: Cisco has a
newer Power Injector (AIR-PWR-INJ5). Can I use this with the AP 1850?
A: The newer
AIR-PWR-INJ5 is a low cost injector for use with the AP 1600 and AP 2600 series
products. It is an 802.3af (15.4 W injector) and will power the AP 1850 at
reduced functionality. It is recommended to use AIR-PWR-INJ4, which is a 30 W
injector, as the AP 1850 draws roughly 20 W for full functionality.
industrial wireless motion or smoke detectors cause WLAN interference?
A: Yes, some
products such as United Technologies DD475 and Optex MX-50 operate in the 2.4
GHz band as do other wireless chimes, cameras, and other industrial equipment
from other manufacturers.
Q: What if I am
in a country where the regulatory agency may not approve the AP to be used
outdoors because of UNII-1 band restrictions or if I wish to use higher gain
A: Consider
deploying the Cisco Mesh products (, and 1530 series) or look for
access points ending in “P” for professional install, such as the 3602P and
3702P series.
Q: Any other
thoughts when installing wireless APs?
installing wireless APs, consider the following:
APs as reasonably close to the actual users as possible.
that you have coverage (to a known requirement) and compensate for nulls or
dead spots regardless of what product you choose to deploy. This is called a
site survey.
Installations should be done based on lessons learned from the
site survey. The better the survey the less likely any connectivity problems
will occur.
an advanced services team that can perform WLAN surveys or help with the
wireless design if a partner is not available or able to do the same.
possible, use Cisco brand antennas listed in this document (with the orange
mount antennas against metal objects. Similar to a light bulb, antennas work
best when there are no obstructions in the path.
, , 3600, and 3700 are not weatherproof and have an IP
rating of 40.
Q: Why am I seeing 6.x.x.x address in CDP Neighbour table on
A: The 1830 and 1850 access points have a default IP address,
in the form 6.x.x.x, which they revert to if they do not receive an IP address
through DHCP. You can see this IP address when you use the command show cdp
neighbor from the connected switch. This IP address will exist until any DHCP
issues in the network are resolved and the APs are assigned an IP address via
ContentsReferences
AP 1850 Product Page and Datasheet
AP 3700 Datasheet
AP and Controller Datasheets
Cisco Antenna Reference Guide
Why Buy Cisco Brand Antennas
Understanding Antenna Patterns and
their Meaning
Cisco Guest Access Deployment Guide
Cisco Schools WLAN Deployment Guide
The Apple Bonjour/Apple TV
Deployment Guide
Optimizing Enterprise Video over
Wireless LAN
Cisco 7925 IP Phone Deployment
Cisco Mobility Services Engine –
WLAN Location Deployment Guide
WLAN Design Guide for High Density
Client Environments in Higher Education
Mobility Design Guides
Software Support and Downloads
New Generation of Cisco Aironet
Access Points
802.11ac Customer Use Cases
Adaptive Radio Modules
New Generation of Cisco Aironet
Access Points
802.11ac Wave-1 Module Datasheet
802.11ac – The Fifth Generation
Wi-Fi Technical Whitepaper
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