For the Cisco 1550 Series
Access Points
As seen in the previous section, we recommend a
cell radius of 600 feet, and an AP to AP distance of 1200 feet. Normally, an AP
to AP distance that is twice the AP to client distance is recommended. That is,
if we halve the AP to AP distance, we will get the approximate cell radius.
The AP1500 series offers
comparatively better range and capacity as it has the 802.11n functionality. It
has advantages of ClientLink (Beamforming) in downstream, better receiver
sensitivities because of MRC in upstream, multiple transmitter streams and a
few other advantages of 802.11n such as channel combining and so on. The 1552
access points can provide comparatively larger and higher capacity cells.
Note 
Link budgets are different
for different country domains. The discussion in this section takes into
account the most widely distributed and large country domains: A and E.

Comparison of Link Budgets of
AP1572 Series and AP1552 Series in 2.4 and 5GHz Bands (A Domain)
See
Table 1.
Table 1 Link Budget Comparison for
the 2.4GHz band in A/B Domain
Parameter

Cisco 1552 (A domain)

Cisco 1532 (A Domain)

Cisco 1562
(A Domain)

Cisco 1572 (B Domain)

Frequency Band

2412 – 2462 MHz

2412 – 2462 MHz

2412–2462 MHz

2412 – 2462 MHz

Air Interface

802.11b/g/n

802.11a//b/g/n/acW2

802.11a/b/g/n/acW2

802.11 a/b/g/n

Channel Bandwidth

20 MHz

20 MHz

—

20 MHz

No. of Tx Spatial Streams

2

3SS for 15621, 2SS for
1562E/D models

3SS for
1562I, 2SS for 1562E/D models

3SS

PHY Data Rates

Up to 144 Mbps^{1}

Up to 216
Mbps with 3SS 144 Mbps for 2SS

Up to 216 Mbps with 3SS
144 Mbps for 2SS

Up to 216
Mbps

Tx Power Conducted

28 dBm, Composite^{2}

29 dBm for 1562I
27 dBm
for 1562E/D

29 dBm
for 1562I
27 dBm
for 1562E/D

30 dBm

Rx Sensitivity

–94 dBm at 6 Mbps
–79 dBm at 54 Mbps
–73 dBm at 150 Mbps

 92 dBm at 6 Mbps
 76 dBm at 54 Mbps
 71 dBm at 216 Mbps

 92 dBm
at 6 Mbps
 76 dBm
at 54 Mbps
 71 dBm
at 216 Mbps

–93 dBm at 6 Mbps
–81 dBm at 54 Mbps
–76 dBm at 216 Mbps

No. of Receive Channels

3

3 or 2

3 or 2

4

Rx Diversity

MRC

MRC

MRC

MRC

Antenna Cable loss

0.5 dB, with external
antenna

0.5 dB external antenna

0.5 dB,
with external antenna

0.5 dB external antenna

^{1} 40MHz channel bonding in 2.4
GHz is not applicable. Therefore, the maximum data rate is 144 Mbps.^{2} Composite power is the
power when we have two Tx streams enabled in AP1552.
For the 5GHz band, see
Table 2.
Table 2 Link Budget Comparison for
the 5GHz band in A/B Domain
Parameter

Cisco 1552 (A Domain)

Cisco 1532 (A Domain)

Cisco 1562
(A/B Domain)

Cisco 1572 (B Domain)

Frequency Band

5745 – 5825 MHz

5.180 –
5.240 GHz
5.260 –
5.320 GHz
5.500 –
5.560 GHz
5.680 –
5.720 GHz
5.745 –
5.825 GHz

5.180 –
5.240 GHz
5.260 –
5.320 GHz
5.500 –
5.560 GHz
5.680 –
5.720 GHz
5.745 –
5.825 GHz

5.180 –
5.240 GHz
5.260 –
5.320 GHz
5.500 –
5.560 GHz
5.680 –
5.720 GHz
5.745 –
5.825 GHz

Air Interface

802.11a/n

802.11a/b/g/n/acW2

802.11a/b/g/n/acW2

802.11a/n/ac

Channel Bandwidth

20 MHz, 40 MHz

20 MHz,
40 MHz, 80 MHz

20 MHz,
40 MHz, 80 MHz

20 MHz, 40 MHz, 80 MHz

No. of Tx Spatial Streams

2

2

3 or 2

3

PHY Data Rates

Up to 300 Mbps

Up to 300 Mbps

1.300 /
867 Mbps

Up to 1.3 Gbps

Tx Power Conducted

28 dBm, Composite

27 dBm

29 or 27
dBm

30 dBm

Rx Sensitivity

–92 dBm at 6 Mbps
–76 dBm at 54 Mbps
–72 dBm at 300 Mbps

–94 dBm at 6 Mbps
–80 dBm at 54 Mbps
–65 dBm at 1300 Mbps

–94 dBm at
6 Mbps
–80 dBm at
54 Mbps
–65 dBm at
1300 Mbps

–92 dBm at 6 Mbps
–80 dBm at 54 Mbps
–60 dBm at 1300 Mbps

The 20MHz channel bonding
to form a 40MHz channel is available in 5 GHz. Therefore, we can go up to a
data rate of 300 Mbps.
As discussed in the
previous section, Path Loss Exponents (PLE) and Link Budget windows work
together. For a full clear path, PLE is 2.0. For AP to AP, there is
comparatively more clearance than AP to client. For AP to AP, PLE can be taken
as 2.3 because it can be assumed that the height of both APs is about 10
meters, which means a good line of sight (but without Fresnel zone clearance).
For AP to client, PLE
should be greater than or equal to 2.5 because the client is only 1 meter high.
Therefore, there will be less Fresnel zone clearance. This applies to both the
2.4GHz and 5GHz bands.
Let us consider AP to AP
link budget in 5 GHz for A domain because 5 GHz is used as a backhaul for
mesh. We can take a legacy data rate of 9 Mbps to estimate the range (see
Table 3).
Note 
This is the lowest data
rate for outdoor 802.11n APs, which carries the Cisco's ClientLink (Beamforming
for Legacy clients) advantage. It provides a gain of up to 4 dB in the downlink
direction.

Table 3 AP to AP RF Link Budget,
5.8 GHz: 9 Mbps (A domain)
Parameter

Cisco 1552 I/C

Cisco 1552 E/H

Tx Power Conducted at 9
Mbps, 20 MHz bandwidth

28 dBm, Composite

26 dBm, Composite

Tx Antenna Cable Loss

0 dB

0.5 dB

Tx Antenna Gain

4 dBi (inbuilt antenna)

7 dBI

Tx Beam Forming (BF)

4 dB

4 dB

Tx EIRP

36 dBm

36.5 dBm

Rx Antenna Gain

4 dBi

7 dBI

Rx Antenna Cable Loss

0 dB

0.5 dB

Rx Sensitivity

–91 dBm at 9 Mbps

–91 dBm at 9 Mbps

System Gain

131 dB

134 dB

Fade Margin

9 dB

9 dB

Range between APs (LOS, PLE
= 2.3)

829 meters (2722 feet)

1120 meters (3675 feet)

A fade margin of 9 dB is
assumed, which is inconsistent with the assumption to calculate the required
SNR values in the
Wireless Mesh
Constraints
section.
Link Budget
Analysis for AP to Client (–A Domain)
This section contains a
link budget analysis for the AP to the Client, so that you know how far away a
client can go from the AP with a system gain value in each band. In this
analysis, the focus is on the system gain for upstream and downstream. A link
should be balanced for upstream and downstream, but it might not happen.
Generally, there is a higher antenna gain and higher Tx power available on the
AP rather than on the client. But, this can also be opposite in a few
regulatory domains because of different EIRP limit requirements. Therefore, the
lowest of both upstream and downstream should be taken to calculate the AP to
the client distance because that will be the decision factor. For example, if
there is a higher downstream gain than upstream, the upstream should be the
decision maker for the cell size because the upstream system gain allows only
the client to connect to the AP.
The regulatory domain
values of Tx EIRP and Rx sensitivities decide whether upstream or downstream
has the lower system gain. The cell size should be determined by upstream and
not downstream.
Because most of the clients
available are 2.4GHz clients, the focus is on the 2.4GHz AP to the.
For the AP to client link
budget in 2.4 GHz, let us assume a client Tx power of 20 dB and an antenna gain
of 0 dBi (see
Table 4).
For the –A domain EIRP limit is 36 dBm for 2.4 and 5GHz bands.
.
Table 4 Outdoor 11n APtoClient,
at 2.4 GHz: 9 Mbps Data Rate (–A domain)
Parameter

Cisco 1552 I/C

Cisco 1552 E/H

Comments


DS

US

DS

US


Tx Power Conducted

28 dBm
(AP)

20 dBm
(Client)

28 dBm
(AP)

20 dBm
(Client)

Composite power at 9 Mbps,
20 MHz bandwidth

Tx Antenna Gain

2 dBi
(AP)

0 dBi
(Client)

4 dBi
(AP)

0 dBi
(Client)


Tx Beam Forming (BF)

4 dB
(AP)

0 dB
(Client)

4 dB
(AP)

0 dB
(Client)

Legacy Rate ClientLink.
Helps only in DS.

Tx EIRP

34 dBm

20 dBm

36 dBm

20 dBm


Rx Antenna Gain

0 dBi
(Client)

2 dBi
(AP)

0 dBi
(Client)

4 dBi
(AP)


Rx Sensitivity

–90 dBm
(Client)

–94 dBm
(AP)

–90 dBm
(Client)

–94 dBm
(AP)

Includes 4.7 dB MRC gain
for AP1552

System Gain

124 dB

116 dB

126 dB

118 dB


Range (AP to Client)


268 meters (881 feet)


323 meters (1058 feet)

LOS, PLE = 2.5

The –A domain AP to client
link budget in 2.4 GHz band is limited by upstream. That is, the upstream has
lower system gain, and therefore, the decision factor will be upstream.
Cell sizes for AP to Client
in 2.4 GHz for different AP1552 models can be decided by picking the lowest of
the following two:
Because most of the clients
available are 2.4GHz clients, we recommend the cell size taking 2.4 GHz values
into consideration (see
Table 5).
Table 5 Lowest of AP to Client and
Half of AP to AP Backhaul Distance
AP Type (A Domain)

AP to Client 2.4 GHz

Half of AP to AP backhaul
Distance in 5 GHz

1552 C/I

250 meters (800 feet)

415 meters (1360 feet)

1552 E/H

300 meters (1000 feet)

560 meters (1840 feet)

For the AP to the AP
distance, you can take double the AP to the client distance (see
Table 6).
Table 6 Recommendations for Cell
Radius
AP Type (A Domain)

AP to Client

AP to AP

1552 C/I

250 meters (800 feet)

500 meters (1600 feet)

1552 E/H

300 meters (1000 feet)

600 meters (2000 feet)

Figure 9. APtoClient Cell Radius at
2.4 GHz
The following assumptions
are made:

Height: APs are at 33 feet
(10 meters); Client at 3.3 feet (1 meter)

Throughput greater than 1
Mbps

Decreasing APtoAP
distance improves coverage

Near LoS. For Less LoS
scenarios, you must reduce the distance assumptions

Flat Terrain Environment
AP Densities result as
follows:
With these recommendations,
the likelihood of getting healthy cells is more.
Note 
For 5GHz clients, the cell
radius is comparatively smaller because higher the frequency, higher is the
attenuation. The 2.4GHz band has almost 13 dB better link budget than 5 GHz.

Comparison of Link Budgets
of AP1520 Series and AP1552 Series in 2.4 and 5GHz Bands (E Domain)
In the E Domain, EIRP
limits are comparatively much lower. EIRP limit for 2.4 Ghz is 20 dBm and for 5
GHz is 30 dBm.
Let us consider 5 GHz
because it is used as a backhaul for mesh. We can take a legacy data rate of 9
Mbps to estimate the range.
Note 
PLE is 2.3 for backhaul.
AP to AP RF Link Budget,
5.6 GHz: 9 Mbps (E domain)

Table 7 AP to AP RF
Link Budget, 5.6 GHz: 9 Mbps (E domain)
Parameter

Cisco 1552 I/C

Cisco 1552 E/H

Tx Power Conducted at 9
Mbps, 20 MHz bandwidth

22 dBm, Composite

19 dBm, Composite

Tx Antenna Cable Loss

0 dB

0.5 dB

Tx Antenna Gain

4 dBi (inbuilt antenna)

7 dBI

Tx Beamforming (BF)

4 dB

4 dB

Tx EIRP

30 dBm

30.5 dBm

Rx Antenna Gain

4 dBi

7 dBI

Rx Antenna Cable Loss

0 dB

0.5 dB

Rx Sensitivity

–91 dBm at 9 Mbps

–91 dBm at 9 Mbps

System Gain

125 dB

127 dB

Fade Margin

9 dB

9 dB

Range between APs (LOS, PLE
= 2.3)

471 meters (1543 feet)

575 meters (1888 feet)

The AP1552 models with
inbuilt antennas (1552C/I) have the same system gain as AP1522s for 5 GHz
backhaul giving the AP to AP distance of 1543 feet.
Link Budget Analysis for AP
to Client (E Domain)
This section contains link
budget analysis for AP to Client in the 2.4GHz band. In this analysis, the
focus is on the system gain for upstream and downstream. Ideally, the link
should be balanced for upstream and downstream, but practically it may not
happen. Therefore, the decision factor for the cell radius will be the lowest
of both upstream and downstream.
For AP to client link
budget in 2.4 GHz, let us assume a client Tx power of 20 dB and an antenna gain
of 0 dBi.
For E domain, the EIRP
limit is 20 dBm for the 2.4GHz band and 30 dBm for the 5GHz band.
Table 8 Outdoor 11n APtoClient,
at 2.4 GHz: 9 Mbps Data Rate (E domain)
Parameter

Cisco 1552 I/C

Cisco 1552 E/H

Comments


DS

US

DS

US


Tx Power Conducted

15 dBm
(AP)

20 dBm
(Client)

13 dBm
(AP)

20 dBm
(Client)

Composite power at 9 Mbps,
20 MHz bandwidth

Tx Antenna Gain

2 dBi
(AP)

0 dBi
(Client)

4 dBi
(AP)

0 dBi
(Client)


Tx Beamforming (BF)

3 dB
(AP)

0 dB
(Client)

3 dB
(AP)

0 dB
(Client)

Legacy Rate ClientLink.
Helps only in DS.

Tx EIRP

20 dBm

20 dBm

20 dBm

20 dBm


Rx Antenna Gain

0 dBi
(Client)

2 dBi
(AP)

0 dBi
(Client)

4 dBi
(AP)


Rx Sensitivity

–91 dBm
(Client)

–94 dBm
(AP)

–91 dBm
(Client)

–94 dBm
(AP)

Includes 4.7 dB MRC gain
for AP1552

System Gain

111 dB

116 dB

111 dB

118 dB


Range (AP to Client)

173 meters (567 feet)


173 meters (567 feet)


LOS, PLE = 2.5 (5 dB fade
margin)

The AP to client link
budget in the 2.4GHz band on the E domain is limited by downstream.
Therefore, downstream has a lower system gain. Thus, the decision factor will
be downstream.
Cell sizes for AP to Client
in 2.4 GHz for different AP1552 models can be decided by picking the lowest of
the following two:
Because most of the clients
available are 2.4GHz clients, we recommend the cell size taking 2.4 GHz values
into consideration (see
Table 9).
Table 9 Lowest of AP to Client and
Half of AP to AP Backhaul Distance
AP Type (E Domain)

AP to Client 2.4 GHz

Half of AP to AP backhaul
Distance in 5 GHz

1552 C/I

180 meters (600 feet)

235 meters (770 feet)

1552 E/H

180 meters (600 feet)

288 meters (944 feet)

For AP to AP distance we
can take double the AP to Client distance (see
Table 10).
Table 10 Recommendations for Cell
Radius
AP Type (E Domain)

AP to Client

AP to AP

1552 C/I

180 meters (600 feet)

360 meters (1200 feet)

1552 E/H

180 meters (600 feet)

360 meters (1200 feet)

Note 
To estimate the range and
the AP density, you can use range calculators that are available at
