Suggestions on Network Planning Practices
Network planning is an important part of WLAN project implementation. The network planning design consists of the following parts:
- Network coverage design: Determine the requirements and principles for signal coverage.
- Network capacity design: Determine the bandwidth requirements of a single user based on the service model and STA behavior, and then determine the number of APs based on the AP capability.
- AP deployment design: Determine AP installation positions based on the deployment principles.
- AP channel planning: Properly plan channels for APs in neighboring areas to reduce co-channel and adjacent-channel interference.
- AP power supply and cabling design
WLAN Coverage Design
Table 3-10 lists the field strength requirements for coverage areas to ensure good coverage.
Coverage |
Field Strength |
Typical Scenario |
|---|---|---|
Major coverage area |
-40 dBm to -65 dBm |
Dorm room, library, classroom, hotel room, lobby, office, and hall |
Common coverage area |
> -75 dBm |
Corridor, kitchen, storeroom, and dressing room |
Special coverage area |
N/A |
Areas that have limitation on or do not allow coverage or installation because of service security or property management |
The coverage suggestions in different scenarios are as follows:
- Indoor scenarios: Plan the coverage radius of 15-20 m for each AP.
- Outdoor scenarios: Plan the coverage radius of 50-80 m for each AP.
- Indoor high-density scenarios: Use small-angle directional antennas. During network planning, select AP positions and spacing based on the antenna angle.
Network Capacity Design
On a WLAN, the bandwidth capacity is calculated based on the following formula:
Total network bandwidth = Average bandwidth required by a single user x Number of users
The bandwidth required by a single STA depends on the actual network application of STAs. Table 3-11 lists the typical bandwidth requirements of common network applications.
Application Type |
Typical Bandwidth Requirement |
Description |
|---|---|---|
Web page browsing |
4 Mbit/s |
Consider images and videos on web pages. |
Video (1080p) |
5 Mbit/s |
Typical value. Bandwidth varies depending on video compression rates and frame rates. |
Audio |
64 kbit/s |
None |
8 Mbit/s |
Consider transfer of large files such as attachments. |
|
File transfer |
10 Mbit/s |
None |
Desktop sharing |
2.5 Mbit/s |
None |
Mobile gaming |
100 kbit/s |
None |
Screen projection |
9 Mbit/s |
None |
Instant messaging |
5 Mbit/s |
Consider the upload of large files such as photos. |
Table 3-12 lists the AP specifications.
Per-User Bandwidth (Mbit/s) |
Recommended Number of Concurrent STAs in Single-Band Mode (One/Two Spatial Streams) |
Recommended Number of Concurrent STAs in Dual-Band Mode (One/Two Spatial Streams) |
|---|---|---|
8 |
5/10 |
9/18 |
6 |
6/11 |
11/20 |
4 |
8/12 |
15/22 |
2 |
12/22 |
22/40 |
1 |
20/30 |
35/55 |
Based on the preceding information (bandwidth requirements of a single STA, number of STAs, and specifications of selected APs), you can calculate the number of APs required in a project.
Deployment Design
Deployment design is involved for APs and access switches on a WLAN.
AP Deployment Guidelines
Comply with the following guidelines when selecting AP deployment positions:
- When installing an AP, try to reduce the number of obstacles that signals traverse.
- Ensure that signals pass through a least number of obstacles such as walls and ceilings.
- Try to make the signals vertically pass through obstacles such as walls and ceilings.
- When an AP is close to a column and radio signals are blocked, a large radio shadow is formed behind the column. When deploying the AP, consider the impact of the column on signal coverage to avoid coverage holes or weak coverage.
- Metal objects have a strong reflection effect on wireless signals. Do not place APs or antennas behind metal ceilings.
- Ensure that the front side of an AP faces the target coverage area.
- If only one AP is required in a lobby, deploy the AP in the central position. If two APs are required, they can be placed diagonally.
- The AP deployment direction is adjustable. Ensure that the front side of an AP faces the target coverage area for good coverage.
- Add APs to the areas that require special attention to ensure signal coverage.
- Deploy APs far from interference sources.
Place APs far away from electronic devices. Do not deploy microwave ovens, wireless cameras, Wi-Fi phones, or other electronic equipment in the coverage area.
- For areas with roaming requirements, keep a 10% to 15% overlapping between the coverage areas of neighboring APs to ensure smooth STA roaming between APs.
- In common indoor scenarios without high aesthetic requirements, APs can be installed directly. In high-end office areas, APs can be installed inside the non-metal ceiling or have an enclosure installed.
The typical AP deployment solutions in different scenarios are described as follows.
- The AP spacing is 10–18 m.
- When more than three APs are required, deploy them in triangle mode.
- This scenario is a common office area scenario.
- This scenario is a school dormitory or hospital ward that features a small room area and high density.
- The agile distributed Wi-Fi solution is recommended, in which an RU or settled AP is deployed in each room.Figure 3-15 Outdoor scenario
- In an open area (with a wide view and few obstacles), deploy APs with omnidirectional antennas for coverage, with a spacing of 50–60 m.
- In areas with obstacles or long narrow areas, deploy APs with large-angle directional antennas for coverage, with a spacing of 30–40 m.
- In the road area, as shown in the left figure above, deploy APs with directional antennas for coverage, with a spacing of 120–150 m.
Access Switch Deployment Guidelines
- It is recommended that an access switch be deployed within 80 m away from the AP cabling.
- Deploy access switches away from strong electromagnetic interference, and take moisture-proof and dust-proof measures.
- Determine the total number of APs based on the number of switch ports, PoE power supply capability of the power module, and AP power consumption.
AP Channel Design
Available channels vary according to local countries and regions. Before network planning, determine locally available channels. For channels in different countries, see WLAN Country Codes and Channels Compliance.
The purpose of channel design is to maximize the distance between APs on the same channel and reduce inter-AP interference. The specific design guidelines are as follows:
- 2.4 GHz channel: In countries that support channels 1–13, channels 1, 6, and 11 are recommended when a small number of APs are deployed. If many APs are required in an area, channels 1, 5, 9, and 13 are recommended.
- 5 GHz channel: When an AP uses a single 5 GHz radio, it is recommended that high and low frequency channels of neighboring APs be staggered. When an AP uses dual 5 GHz radios, it is recommended that two 5 GHz radios be planned at low and high frequencies respectively.
- In the case of multiple floors, avoid overlapping with channels of APs at adjacent floors. If channel overlapping cannot be avoided, reduce AP power to minimize the overlapping areas.Figure 3-16 Typical channel design diagram
The following figure shows an example of 2.4 GHz channel planning for multi-floor coverage.
Figure 3-17 Example of 2.4 GHz channel planning for multi-floor coverage
AP Power Supply and Cabling Design
Power supply modes:
- Power supply by PoE devices (recommended)
A PoE switch is used for data transmission and power supply of APs, and is the main power supply mode for the APs.
- Local power supply
An independent power supply is used to supply power to APs. In most cases, a local AC power supply can be used to supply power to APs if an uplink switch does not support PoE power supply.
- Power supply by PoE adapters
Outdoor APs use optical fibers for data transmission and support only PoE power supply. In this case, PoE adapters are used to supply power to APs. In outdoor scenarios, PoE adapters must be installed in an equipment container or cabinet to meet the operating temperature, waterproof, and surge protection requirements.
Figure 3-18 AP power supply modesCabling design guidelines:
- During AP deployment, reserve around 5 m network cable for adjusting AP installation positions due to interference or poor signal coverage in the future.
- Keep network cables far away from strong electromagnetic interference.
- Confirm with customers about the cabling design in advance to prevent customers from disallowing construction for the property or appearance reason.
