The Cisco Aironet 1550 Series Outdoor Mesh Access Point is a modularized wireless outdoor 802.11n access point designed for use in a mesh network. The access point supports point-to-multipoint mesh wireless connectivity and wireless client access simultaneously. The access point can also operate as a relay node for other access points that are not directly connected to a wired network. Intelligent wireless routing is provided by the Adaptive Wireless Path Protocol (AWPP). This enables the access point to identify its neighbors and intelligently choose the optimal path to the wired network by calculating the cost of each path in terms of signal strength and the number of hops required to get to a controller.

The 1550 series access points leverage 802.11n technology with integrated radio and internal/external antennas. The 1552 outdoor platform consists of Multiple Input Multiple Output (MIMO) WLAN radios. It offers 2x3 MIMO with two spatial streams, Beamforming, and comes with integrated spectrum intelligence (CleanAir).

CleanAir provides full 11n data rates while detecting, locating, classifying, and mitigating radio frequency (RF) interference to provide the best client experience possible. CleanAir technology on the outdoor 11n platform mitigates Wi-Fi and non-Wi-Fi interference on 2.4-GHz radios.

The 1550 series access points have two radios—2.4-GHz and 5-GHz MIMO radios. While the 2.4-GHz radios are used primarily for local access, the 5-GHz radios are used for both local access and wireless backhaul in mesh mode.

Note	The wIPS submode is not supported on the Cisco 1552 Series Mesh Access Points.

Note	The 2.4-GHz radios cannot be used for backhaul in 1552 APs.

The 2-GHz b/g/n radio has the following features:

• Operates in the 2.4-GHz ISM band.
• Supports channels 1-11 in the United States, 1-13 in Europe, and 1-13 in Japan.
• Has two transmitters for 802.11b/g/n operation.
• You can configure the output power for 5 power levels.
• The radio has three receivers that enable maximum-ratio combining (MRC).

The 5-GHz a/n radio has the following feature:

• Operates in the UNII-2 band (5.25 to 5.35 GHz), UNII-2 Extended/ETSI band (5.47 to 5.725 GHz), and the upper ISM band (5.725 to 5.850 GHz).
• Has two transmitters for 802.11a operation.
• Power settings can change depending on the regulatory domain. You can configure the output power for 5 power levels in 3 dB steps.
• The radio has three receivers that enable maximum-ratio combining (MRC).

The 1550 series access points have the following features:

• Supports modularity of the 1520 series and allows flexibility in radio configuration
• Fully interoperable with the 1520 series access points
• Can also interoperate with legacy clients and offers enhanced backhaul performance
• Multicast VideoStream and HotSpot 2.0 are supported when the AP is configured in Local mode.
• AP1552 is QoS capable of supporting quality VoWLAN calls.
• Band Select, which notifies a connected client to roam from 2.4 GHz to 5 GHz, is supported.
• DTLS support allows AP1552 to encrypt data in all supported AP modes except Bridge mode.
• You can enable CleanAir on the 5-GHz radio by navigating to Wireless > Radios > 802.11a > Configure on the controller GUI.
• If AP1552 is in Bridge mode, CleanAir Advisor becomes operational. CleanAir Advisor generates CleanAir reports and identifies interference. The event driven RRM is disabled. Therefore, the radio does not change the transmission power level or channel.

The models can be classified as models with external antennas and models with built-in antennas. The 1552C model is configured with an integrated DOCSIS/EuroDOCSIS 3.0 cable modem. The DOCSIS 3.0 cable modem provides 8 DS and 4 US (8x4), 304x108 Mbps. The EuroDOCSIS 3.0 cable modem provides 4 US and 4 DS (4x4), 152x108 Mbps. While a DOCSIS 2.0 cable modem could provide throughput of up to 40 Mbps only, a DOCSIS 3.0 cable modem can provide a DS throughput of 290 Mbps and a US throughput of 100 Mbps.

For more information about the Cisco 1550 Series Access Points, see http:/​/​www.cisco.com/​en/​US/​products/​ps11451/​index.html.

The AP1522 mesh access point (part numbers: AIR–LAP1522AG–X–K9, AIR–LAP1522HZ–X–K9, AIR–LAP1522PC–X–K9) includes two radios: a 2.4-GHz and a 4.9- to 5.8-GHz radio. The 2.4-GHz (802.11b/g) radio is for client access and the 5-GHz (802.11a) radio is used as the backhaul. With the 7.0.116.0 release and later releases, 2.4 GHz is available for backhaul. This feature is applicable only to AP1522.

The 5-GHz radio is a 802.11a radio that covers the 4.9- to 5.8-GHz frequency band and is used as a backhaul. It can also be used for client access if the backhaul client access feature is enabled.

Note	AP1522s with serial numbers prior to FTX1150XXXX do not support 5- and 10-MHz channels on the 4.9-GHz radio; however, a 20-MHz channel is supported.

Note	Those AP1522s with serial numbers after FTX1150XXXX support 5-, 10-, and 20-MHz channels.

The AP1524PS mesh access point (part number: AIR–LAP1524PS–X–K9) includes three radios: a 2.4-GHz, a 5.8-GHz, and a 4.9-GHz radio. The 2.4-GHz radio is for client access (nonpublic safety traffic) and the 4.9-GHz radio is for public safety client access traffic only. The 5.8-GHz radio can be used as the backhaul for both public safety and nonpublic safety traffic.

The 4.9-GHz and 5.8-GHz radios are 802.11a subband radios that support a subset of specific 802.11a channels and include a subband specific filter designed to lessen interference from other 11a subband radios within the same mesh access point.

The 4.9-GHz subband radio on the AP1524 supports public safety channels within the 5-MHz (channels 1 to 10), 10-MHz (channels 11 to 19), and 20-MHz (channels 20 to 26) bandwidths.

• The data rates supported within the 5-MHz bandwidth are 1.5, 2.25, 3, 4.5, 6, 9, 12, and 13.5 Mbps. The default rate is 6 Mbps.
• The data rates supported within the 10-MHz bandwidth are 3, 4.5, 6, 9, 12, 18, 24, and 27 Mbps. The default rate is 12 Mbps.

The AP1524SB mesh access point (part number: AIR–LAP1524SB–X–K9) includes three radios: one 2.4-GHz radio and two 5-GHz radios.

The 2.4-GHz radio is for client access (nonpublic safety traffic). The two 5-GHz radios serve as serial backhauls: one uplink and one downlink. The AP1524SB is suitable for linear deployments.

Note	In the 6.0 release, the 5-GHz radios in the –A domain could be operated only in the 5.8-GHz band with 5 channels. In the 7.0 release, these radios cover the whole 5-GHz band.

Each 5-GHz radio backhaul is configured with a different backhaul channel. There is no need to use the same shared wireless medium between the north-bound and south-bound traffic in a mesh tree-based network.

On the RAP, the radio in slot 2 is used to extend the backhaul in the downlink direction; the radio in slot 1 is used only for client access and not mesh.

On the MAP, the radio in slot 2 is used for the backhaul in the uplink direction; the radio in slot 1 is used for the backhaul in the downlink direction.

You only need to configure the RAP downlink (slot 2) channel. The MAPs automatically select their channels from the channel subset. The available channels for the 5.8-GHz band are 149, 153, 157, 161, and 165.

Figure 2. Channel Selection Example. This figure shows an example of channel selection when the RAP downlink channel is 153.

Fall Back Mode

Slot 1 in a 5-GHz radio in a MAP can act as an uplink radio for the backhaul in any one of the following scenarios:

• Slot 2 radio fails.
• Antenna for slot 2 radio goes bad.
• Slot 2 radio is unable to find the uplink because of a bad RF design.
• Interference and long-term fades disturb the uplink to the extent that the slot 2 radio loses its uplink connection.

When a slot 1 radio takes over a slot 2 radio, it is called Fall Back Mode. The slot 2 radio is made inactive on a noninterfering channel. The hardware is reduced to AP1522 (two radios). The slot 1 radio (omni antenna) is extended to the uplink. A period of 15 minutes is set on a timer to attempt a rescan to find a parent on the slot 2 radio again. The timer is similar to the default BGN timer.

Figure 3. Fall Back Mode. This figure shows an example of the Fall Back Mode.

The antenna ports are labeled on the AP1524SB and are connected internally to the radios in each slot. The AP1524SB has six ports with three radio slots (0, 1, 2) as described in Table 1.

Table 1 AP1524SB Antenna Ports

Antenna Port	Radio Slot	Description
1	1	5 GHz–Used for backhaul and universal access. Universal access is configured only on slot 1. Note    Omni antenna is required.
2	0	2 GHz–Used for client access.
3	0	2 GHz–Used for client access.
4	0	2 GHz–Used for client access.
5	—	Not connected.
6	2	5 GHz–Used for backhaul. Note    Directional antenna is required.

Note

Depending on the product model, the AP1524SB could have either 5-GHz radios or 5.8-GHz subband radios installed in slot 1 and slot 2. Regardless of the radios installed, the AP1524SB running controller software release 6.0 is restricted to the UNII-3 channels (149, 153, 157, 161, and 165) in slot 1 and slot 2.

AP1500s support four Gigabit Ethernet interfaces.

• Port 0 (g0) is a Power over Ethernet (PoE) input port–PoE (in)
• Port 1 (g1) is a PoE output port–PoE (out)
• Port 2 (g2) is a cable connection
• Port 3 (g3) is a fiber connection

You can query the status of these four interfaces in the controller CLI and Cisco Prime Infrastructure.

In the controller CLI, the show mesh env summary command is used to display the status of the ports.

• The Up or Down (Dn) status of the four ports is reported in the following format:
  • port0(PoE-in):port1(PoE-out):port2(cable):port3(fiber)
• For example, rap1522.a380 in the display below shows a port status of UpDnDnDn. This indicates the following:
  • PoE-in port 0 (g0) is Up, PoE-out port 1 (g1) is Down (Dn), Cable port 2 (g2) is Down (Dn), and Fiber port 3 (g3) is Down (Dn).

    
    (controller)> show mesh env summary
    AP Name      Temperature(C/F) Heater Ethernet Battery
    --------     --------------- -------- ------- -------
    rap1242.c9ef    N/A            N/A    UP       N/A
    rap1522.a380    29/84          OFF    UpDnDnDn N/A 
    rap1522.4da8    31/87          OFF    UpDnDnDn N/A
    

Battery backup six-ampere hour module is available for the following:

• AIR-1520-BATT-6AH for AP1520s
• AIR-1550-BATT-6AH for only the AIR-CAP-1552E-x-K9 model

The integrated battery can be used for temporary backup power during external power interruptions.

The battery run time for AP1520s is as follows:

• 3-hour access point operation with up to 3 radios at 77oF (25oC) with PoE output port off
• 2-hour access point operation with up to 3 radios at 77oF (25oC) with PoE output port on

The battery run time for AP1550s is as follows:

• 2-hour access point operation using two radios at 77oF (25oC) with PoE output port off
• 1.5-hour access point operation using two radios at 77oF (25oC) with PoE output port on

The battery pack is not supported on the access point cable configuration.

Note	For a complete listing of optional hardware components for AP1520s such as mounting brackets, power injectors, and power tap adapters, see http:/​/​www.cisco.com/​en/​US/​prod/​collateral/​wireless/​ps5679/​ps8368/​product_​data_​sheet0900aecd8066a157.html

A 1500 series access point has a reset button located on the bottom of the unit. The reset button is recessed in a small hole that is sealed with a screw and a rubber gasket. The reset button can be used to perform the following functions:

• Reset the access point—Press the reset button for less than 10 seconds, and the LEDs turn off during the reset and then reactivate when the reset is complete.
• Disable battery backup power—Press the reset button for more than 10 seconds, and the LEDs turn off, then on, and then stay off.
  • You can also disable the battery remotely by entering the following command: config mesh battery-state disable AP_name
• Switch off LEDs—Press the reset button for more than 10 seconds, and the LEDs turn off, then on, and then stay off.

Figure 4. Reset Button Location - Models AIR-CAP1552E-x-K9 and AIR-CAP1552H-x-K9

Figure 5. Reset Button Location - Models AIR-CAP1552C-x-K9 and AIR-CAP1552I-x-K9

Figure 6. Reset Button Location for 1520 Series

The four-status LEDs on AP1500s are useful during the installation process to verify connectivity, radio status, access point status, and software status. However, once the access point is up and running and no further diagnosis is required, we recommend that you turn off the LEDs to discourage vandalism.

If your access point is not working as expected, see the LEDs at the bottom of the unit. You can use them to quickly assess the status of the unit.

Note	LEDs are enabled or disabled using the config ap led-state {enable | disable} {cisco_ap_name | all} command.

There are four LED status indicators on AP1500s.

Figure 7. Access Point LEDs at the Bottom of the Unit. This figure shows the location of the AP1500 LEDs.

The table below describes each LED and its status.

Note

The RF-1 and RF-2 LEDs monitor two radios simultaneously but do not identify the affected radio. For example, if the RF-1 LED displays a steady red LED, one or both of the radios in slots 0 and 2 have experienced a firmware failure. To identify the failing radio, you must use other means, such as the access point CLI or controller GUI to investigate and isolate the failure.

Table 1 lists the access point LED signals.

In the 7.0 release, new 1524 SKUs are released, with both 802.11a radio units supporting the entire 5-GHz band from 4.9 GHz to 5.8 GHz. This release also opens the 5-GHz band for the -A domain as well on the existing hardware. The radios can also operate in UNII-2 (5.25 to 5.35 GHz), UNII-2 plus (5.47 to 5.725 GHz), and the upper ISM (5.725 to 5.850 GHz) bands.

The public safety band (4.94 to 4.99 GHz) is not supported for backhaul and for client access.

For information about the channels and maximum power levels of the AP1500 supported within the world's regulatory domains, see the Channels and Maximum Power Settings for Cisco Aironet Lightweight Access Points manual at:

• AP1520: http:/​/​www.cisco.com/​en/​US/​docs/​wireless/​access_point/​channels/​lwapp/​reference/​guide/​1520_​chp.html

Table 1 provides a complete overview of channels supported in each domain. In addition to 5 channels in the upper ISM band, there are 4 channels in the UNII-2 band and 11 channels in the UNII-2 Plus band. For outdoor APs, there are 5 channels in the upper ISM band, 3 channels in the UNII-2 band, and 8 channels in the UNII-2 Plus band.

With the expansion of the channel set, DFS-enabled channels are also supported. Radar detection and automatic channel reassignment in case of radar detection on RAP/MAPs are also supported. When there is a channel change, it is also propagated to the corresponding parent/child access point (if applicable) so that the channel change is synchronized between the parent and child so that there is no link downtime. For example, if radar is detected on the uplink radio of a child access point, the parent is informed so that it can change the channel of the downlink radio. The parent in turn informs the child about the channel change, so that the child access point can set the new channel on its uplink radio as well and does not have to scan again to rejoin the parent on the new channel.

For countries in the Middle East such as Saudi Arabia and Kuwait, a new regulatory domain for outdoor APs, the -M domain, has been mandated. With this release, outdoor APs will now support this new -M domain. Earlier, these countries were part of the -E domain, which supported a channel set of 100 to 140. However, in the -M domain, channels 149 to 161 are also supported with the 100 to 140 band. Also, in the -M domain, channels 149 to 161 are DFS enabled, unlike other domains such as -A, -C, -N, and so on, where these channels are non-DFS. Radar detection is also enabled on these channels. Because the countries that are now part of the -M domain (that is, Saudi Arabia and Kuwait) were earlier part of the -E domain, both the -E domain and the -M domain APs are supported, when any of these countries is configured on the controller, which ensures backward compatibility with the existing -E domain APs in these countries. However, you will have to ensure that only a valid set of channels (the channels common to both the -E and the -M domains) is selected as part of the 802.11a DCA list, and that the backhaul channel deselection feature is enabled to ensure correct operation of the -E domain APs, as these APs can support 100 to 140 channels and not the extended list of 149 to 161 channels available in the -M domain.

With the 7.0 release, in AP1522 and AP1524SB platforms, in addition to the 5 channels in the upper ISM band, there are 3 channels in the UNII-2 band and 8 channels in the UNII-2 Extended band. There are 11 channels in the UNII-2 Extended band, but only 8 are applicable in the outdoors due to stringent dynamic frequency selection (DFS) conditions for Canada because Canada requires a channel availability check every 10 minutes compared to every 60 seconds in the USA. The 120 (5600 MHz), 124 (5620 MHz), and 128 (5640 MHz) channels have had to be dropped.

The Federal Communications Commission (FCC) has issued a guideline to protect Terminal Doppler Weather Radar (TDWR) systems operating in the 5600- to 5650-MHz band from interference. Also, the UNII-2 Wi-Fi operating channels are interfering with the TDWR band. Therefore, with the 7.0.116.0 release, the 116 and 132 channels are dropped in addition to the 120, 124, and 128 channels. The guidelines also require that you avoid operation in the TDWR band and operate at least 30 MHz away from the TDWR operation frequencies when devices are installed within 35 km (about 21 miles) or the line-of-sight of the TDWR sites.

Note	Your outdoor installation should be registered in the outdoor database. No fee is required to register your company. The TDWR location sites can be found on the Internet.

Note

The FCC, the National Telecommunications and Information Administration (NTIA), and the Federal Aviation Administration (FAA) are continuing to investigate and eliminate cases of interference to TDWRs. For more information about FCC guidelines for outdoor installations, see http:/​/​www.cisco.com/​en/​US/​prod/​collateral/​routers/​ps272/​data_​sheet_​c78-647116_​ps11451_​Products_​Data_​Sheet.html.

Both the 2.4-GHz and 5-GHz frequency bands are supported on the indoor and outdoor access points. Additionally, the 4.9-GHz public safety band is supported on AP1524PS.

Figure 8. Frequency Bands Supported By 802.11a Radios on AP1520s

The 5-GHz band is a conglomerate of three bands in the USA: 5.150 to 5.250 (UNII-1), 5.250 to 5.350 (UNII-2), 5.470 to 5.725 (UNII-2 Extended), and 5.725 to 5.850 (ISM). UNII-1 and the UNII-2 bands are contiguous and are treated by 802.11a as being a continuous swath of spectrum 200-MHz wide, more than twice the size of the 2.4-GHz band (see Table 1).

The 4.9 GHz is a public safety channel within the 5-MHz (channels 1 to 10), 10-MHz (channels 11 to 19), and 20-MHz (channels 20 to 26) bandwidths.

Note	The frequency depends on the regulatory domain in which the access point is installed. For additional information, see the Channels and Power Levels document at http:/​/​www.cisco.com/​en/​US/​docs/​wireless/​access_point/​channels/​lwapp/​reference/​guide/​lw_​chp2.html.

Note

The 1552 access points support only the ISM band in the -A domain. The 1552 access points support the UNII-2 and UNII-2 Extended bands. The DFS algorithms work as expected. The DFS algorithms can be implemented in the ETSI and other domains, but not in the -A domain. The product certification is pending the FCC approval and it might take up to 4 months to get the product certified. After the product is certified, Cisco will provide new software that will allow the UNII-2 and UNII-2 Extended bands to be used for the 1552 access points in the -A domain.

For regulatory information, see http:/​/​www.cisco.com/​en/​US/​prod/​collateral/​wireless/​ps5679/​ps5861/​product_​data_​sheet0900aecd80537b6a.html.

Previously, devices employing radar operated in frequency subbands without other competing services. However, controlling regulatory bodies are attempting to open and share these bands with new services like wireless mesh LANs (IEEE 802.11).

To protect existing radar services, the regulatory bodies require that devices wishing to share the newly opened frequency subband behave in accordance with the Dynamic Frequency Selection (DFS) protocol. DFS dictates that to be compliant, a radio device must be capable of detecting the presence of radar signals. When a radio detects a radar signal, it is required to stop transmitting to for at least 30 minutes to protect that service. The radio then selects a different channel to transmit on but only after monitoring it. If no radar is detected on the projected channel for at least one minute, then the new radio service device may begin transmissions on that channel.

The AP performs a DFS scan on the new DFS channel for 60 seconds. However, if a neighboring AP is already using that new DFS channel, the AP doesnot perform the DFS scan.

The process for a radio to detect and identify a radar signal is a complicated task that sometimes leads to incorrect detects. Incorrect radar detections can occur due to a large number of factors, including due to uncertainties of the RF environment and the ability of the access point to reliably detect actual on-channel radar.

The 802.11h standard addresses DFS and Transmit Power Control (TPC) as it relates to the 5-GHz band. Use DFS to avoid interference with radar and TPC to avoid interference with satellite feeder links.

Note	DFS is mandatory in the USA for 5250 to 5350 and 5470 to 5725 frequency bands. DFS and TPC are mandatory for these same bands in Europe.

Figure 9. DFS and TPC Band Requirements

The 1552 access point supports the following two types of antennas designed for outdoor use with radios operating in the 2.4-GHz and 5-GHz frequency:

• Cisco Aironet Low Profile Dual-Band 2.4/5 GHz Dipole Antenna Array (CPN 07-1123-01), an integrated array of three dual-band dipole antennas
• Cisco Aironet Dual-Band Omnidirectional Antenna (AIR-ANT2547V-N), referred to as “stick” antennas

Two types of mounting configurations are available: the cable strand mount and the pole mount.

The 1552 models C and I access points are equipped with three new integrated dual-band antennas, with 2 dBi gain at 2.4 GHz and 4 dBi gain at 5 GHz. The antenna works in cable strand mount and low cost, low profile applications.

Figure 13. 1552C Cable Mount

Figure 14. 1552I Pole/Wall Mount

The 1552 E and H access points are equipped with three N-type radio frequency (RF) connectors (antenna ports 4, 5, and 6) on the bottom of the unit for external antennas to support multiple input multiple output (MIMO) operation as shown in the figure below. When using the optional Cisco Aironet AIR-ANT2547V-N Dual-Band Omnidirectional Antenna, the 2.4- and 5-GHz antennas connect directly to the access point. These antennas have 4 dBi gain at 2.4 GHz and 7 dBi gain at 5 GHz.

Figure 15. 1552 E Pole/Wall Mount

Figure 16. Outdoor Pole-top Installation of a Mesh Access Point. This figure shows one of the recommended installations of an outdoor AP1500.

The AP1500 series was designed building on the long experience we have had in deploying outdoor access points over the past few years. This includes consideration for resistance to lightning effects. The AP1500 series employs some lightning arrestor circuitry on the Ethernet & Power ports. On input Ethernet port, Gas Discharge Tubes (GDT) are used on the Power Entry Module (PEM) to mitigate lightning effect. On the AC Power, GDTs are also used along with fuses to mitigate a high-current condition. For the DC power, a fuse is used to mitigate a high-current condition.

While not a common practice, users may want to consider adding additional lightning protection at the antenna ports for added protection.

You can use third-party antennas with AP1500s. However, note the following:

• Cisco does not track or maintain information about the quality, performance, or reliability of the noncertified antennas and cables.
• RF connectivity and compliance is the customer’s responsibility.
• Compliance is only guaranteed with Cisco antennas or antennas that are of the same design and gain as Cisco antennas.
• Cisco Technical Assistance Center (TAC) has no training or customer history with regard to nonCisco antennas and cables.

To understand how this works, consider a single transmitter 802.11a/g client sending an uplink packet to an 802.11n access point with multiple transceivers. The access point receives the signal on each of its three receive antennas.

Each received signal has a different phase and amplitude based on the characteristics of the space between the antenna and the client. The access point processes the three received signals into one reinforced signal by adjusting their phases and amplitudes to form the best possible signal. The algorithm used, called maximum ratio combining (MRC), is typically used on all 802.11n access points. MRC only helps in the uplink direction, enabling the access point to "hear" the client better.

Figure 17. Reinforcement of Received Signal via MRC Algorithm

For the 1550 Series

In the 1552 series mesh access point, MRC gain is different than the 1520 series mesh access points. The 1520 series access points do not have 802.11n functionality. In the 2.4-GHz band, it has only one transmitter and up to three receivers. Therefore, it is SIMO (Single in Multiple out) in 2.4 GHz. In the 5-GHz band, it has only one transmitter and one receiver. Therefore, it is SISO (Single in Single out) in the 5-GHz band. The MRC gain is important only for the 2.4-GHz radio in the 1552 access points. The MRC is not available for the 5-GHz radio. The 2.4-GHz radio has one Tx and up to three Rx antennas depending on the AP configuration.

In the 1522 access points, users have an option to use one, two, or three 2.4-GHz Rx antennas. With this option, users get around 3 dB MRC gain with 2 Rx antennas and a 4.5-dB MRC gain with 3 Rx antennas for data rates of 24 Mbps or higher.

For the 1552 access points, both the 2.4- and 5-GHz radios are 2x3 MIMO. Therefore, they have two transmitters and three receivers. Because the antennas are dual band and there is no option to have less than three Rx antennas, the MRC is added to the RX sensitivity always as it is embedded into the baseband chipset.

The number for typical Rx sensitivity in our customer data sheet assume 3 Rx antennas for both the 1520 and the 1550 series access points.

With the chipset used in the AP1520 series radios, there was a start-of-packet problem at lower data rates that wiped out the gain. Therefore, the MRC gain became useful from a data rate of 12 Mbps onwards in the 1520 series access points. This problem has been corrected in the current chipset used in the 1552 access points. The MRC gain has improved for lower data rates as well in the 1552 access points. You get a 4.7-dB improvement in sensitivity with the 2x3 MIMO radio over a 1x1 SISO implementation.

Table 2 and Table 3 list the MRC gain for the AP1552 11a/g and AP1552 11n respectively.

Table 9 AP1552 11a/g MRC Gain

11a/g MCS (Mbps)	Modulation	MRC Gain from 3 RXs (dB)
6	BPSK 1/2	4.7
9	BPSK 3/4	4.7
12	QPSK 1/2	4.7
18	QPSK 3/4	4.7
24	16QAM 1/2	4.7
36	16QAM 3/4	4.7
48	64QAM 2/3	4.7
54	64QAM 3/4	4.7

Table 10 AP1552 11n MRC Gain

No. of Spatial Streams	11n MCS	Modulation	MRC Gain from 3 RXs (dB)
1	MCS 0	BPSK 1/2	4.7
1	MCS 1	QPSK 1/2	4.7
1	MCS 2	QPSK 3/4	4.7
1	MCS 3	16QAM 1/2	4.7
1	MCS 4	16QAM 3/4	4.7
1	MCS 5	64QAM 2/3	4.7
1	MCS 6	64QAM 3/4	4.7
1	MCS 7	64QAM 5/6	4.7
2	MCS 8	BPSK 1/2	1.7
2	MCS 9	QPSK 1/2	1.7
2	MCS 10	QPSK 3/4	1.7
2	MCS 11	16QAM 1/2	1.7
2	MCS 12	16QAM 3/4	1.7
2	MCS 13	64QAM 2/3	1.7
2	MCS 14	64QAM 3/4	1.7
2	MCS 15	64QAM 5/6	1.7

Note	With two spatial streams, the MRC gain is halved, that is the MRC gain is reduced by 3 dB. This is because the system has 10 log (3/2 SS) instead of 10 log (3/1 SS). If there were to have been 3 SS with 3 RX, then the MRC gain would have been zero.

The standard AP1500 enclosure is a ruggedized, hardened enclosure that supports the NEMA 4X and IP67 standards for protection to keep out dust, damp and water.

Hazardous Certification (Class 1, Div 2, and Zone 2)

To operate in occasional hazardous environments, such as oil refineries, oil fields, drilling platforms, chemical processing facilities, and open-pit mining, special certification is required and the certification is labeled as Class 1, Div 2, or Zone 2.

Note	For USA and Canada, this certification is CSA Class 1, Division 2. For Europe (EU), it is ATEX or IEC Class 1, Zone 2.

Cisco has Hazardous Certified SKUs for USA and EU: AIR-LAP1522HZ-x-K9, AIR-LAP1524HZ-x-K9, and AIR-LAP1552H-x-K9. These SKUs are modified, as per the certification requirements. The hazardous locations certificate requires that all electrical power cables be run through conduit piping to protect against accidental damage to the electrical wiring that could cause a spark and possible explosion. Access points for hazardous locations contain an internal electrical mounting connect that receives discrete wires from a conduit interface coupler entering from the side of the housing. After the electrical wiring is installed, a cover housing is installed over the electrical connector to prevent exposure to the electrical wiring. The outside of the housing has a hazardous location certification label (CSA, ATEX, or IEC) that identifies the type of certifications and environments that the equipment is approved for operation.

Note	Power entry module for CSA (USA and Canada) is Power Entry Module, Groups A, B, C, and D with T5v(120° C) temp code. Power Entry Module for ATEX (EU) is Power entry module Groups IIC, IIB, IIA with T5 (120° C) temp code.

Hazardous Certification (Div 1 > Div 2 and Zone 1 > Zone 2)

Class 1, Division 1/Zone 1 is for environments with full-time ignitable concentrations of flammable gases, vapors, or liquids. To meet the requirements of the Div 1 > Div 2 and Zone 1 > Zone 2 locations, we recommend a TerraWave Solutions CSA certified protective Wi-Fi enclosure (see Table 1).

Table 11 TerraWave Enclosures

Access Points	Enclosure Part No	Description
Indoor Mesh Access Points (Cisco Aironet 1040, 1130, 1140, 1240, 1250, 1260, 3500e, and 3500i series access points)	Example: TerraWave XEP1242 for 1240 series.	18 x12 x8 Protective Wi-Fi Enclosure that includes the Cisco 1242 Access Point
Outdoor Mesh Access Points (1522, 1524, 1552)	Example: TerraWave Part Number: XEP1522	18 x 12 x8 Protective Wi-Fi Enclosure that includes the Cisco 1522 Access Point

For more information about the TerraWave enclosures, see http:/​/​www.tessco.com/​yts/​partner/​manufacturer_list/​vendors/​terrawave/​pdf/​terrawavehazardouesenclosuresjan08.pdf

Table 2 lists the hardware features across different AP1500 models at a glance.

Table 12 Hardware Features at a Glance

Features	1552E	1552H	1552C	1552I	152X (1522, 1524SB, 1524PS)
Number of radios	2	2	2	2	2 (1522), 3 (1524)
External Antennas	Yes	Yes	—	—	Yes
Internal Antennas	—	—	Yes	Yes	—
CleanAir 2.4-GHz radio	Yes	Yes	Yes	Yes	—
CleanAir 5-GHz radio	—	—	—	—	—
Beam Forming (ClientLink)	Yes	Yes	Yes	Yes	—
Fiber SFP	Yes	Yes	—	—	Yes
802.3af PoE out port	Yes	Yes	—	—	Yes
DOCSIS 3.0 Cable Modem	—	—	Yes	—	—
DOCSIS 2.0 Cable Modem	—	—	—	—	Yes
HazLoc Class 1 Div 2/Zone 2	—	Yes	—	—	Yes
Battery backup option	Yes	Yes	—	—	Yes
Power options	AC, DC, Power Injector	AC, DC, Power Injector	40 to 90 VAC Power over Cable	AC, DC	AC, DC, 40 to 90 VAC Power over Cable
Heater	—	—	—	—	Yes (1522C)
Console Port Ext. Access	Yes	Yes	Yes	Yes	Yes Note    You need to open the access point.

Note	PoE-in is not 802.3af and does not work with PoE 802.3af-capable Ethernet switch. It requires Power Injector.