An Alibaba Engineer’s 30 Minute Solution to Improve Your Home’s Wi-Fi

  • Egress: An Ethernet network cable is delivered to the user at the egress side by the telecom carrier, that is just to say that a network cable brings the Internet to you. This Ethernet network cable also includes the household fiber, such as the Passive Optical Network (PON) terminals and egress routers. It provides features such as PPPOE dial-up and secure access control based on Network Address Translation (NAT), which functions by translating the IP address of your household network, that is your private network, to the IP address of the carrier network, or public network, which is how your network stays connected to the greater network infrastructure of the Internet.
  • Core area: This area is the center from which all network devices are interconnected and the backbone channel of the household network. Generally, it is a router or switch that provides functions such as CIDR block or route intercommunication, Dynamic Host Configuration Protocol (DHCP), Internet behavior management, speed limiting, and security. It also allows direct connection by wired devices and provides large-traffic input and output capabilities, such as your home NAS, video recorders, and server connections.
  • Access area: This is the most user-oriented area of the network. In it deployed are network edge devices that can interconnect with terminals, which is just a fancy way of saying mobile phones, computers, and IoT devices, such as a smart speaker or smart thermostat. This is usually a port of a wireless router access point or a switch.

Symptoms of Wi-Fi Failures

  • Symptom 1: The Wi-Fi network has problems such as network disconnection, packet loss, lag, sudden speed changes, high jitter, and instability.
  • Symptom 2: The network is slow. The network is still slow after high bandwidth and high-power wireless routers are added.
  • Symptom 3: The mobile phone in bedroom A often connects to the router in bedroom B. In this case, although the displayed signal strength is high, the actual network connection is slow.

Wi-Fi Signal Optimization Principles

  • Two-way communication: When only one-way communication is necessary, one transmission tower of the radio broadcasting base station is enough to cover an entire city, and one loudspeaker is needed to cover an entire village. This is the core advantage of one-way communication. When two-way communication is required, as when making a phone call, we need to compress the voice obtained by the microphone on the mobile phone into a radio wave signal and return it to the communication base station. The signal quality is subject to the power of the mobile phone, that is, the effective transmit distance. Due to the low transmission power of mobile phones, mobile carriers need to deploy a large number of communication base stations in a cellular network to effectively receive the backhaul from the terminal and achieve effective two-way communication. Wi-Fi also uses radio waves propagated through the air, and thus works in a similar manner.
  • Cellular design: In principle, the closer the two parties during radio communication, the higher the bandwidth the two parties can negotiate. The currently commonly used 5-GHz Wi-Fi protocol mainly runs at the 5.2 GHz to 5.8 GHz band, with a theoretical communication bandwidth of up to 1.3 Gbit/s. It is mainly designed for small indoor cellular networks. In addition, considering the mobile phone antenna and exterior, battery usage time, and power consumption, most mobile phones on the market currently offer a power of somewhere between 10 to 14 dB, as shown in the following figure. Most Intel Wi-Fi network cards in laptops have a power of 12–14 dB.
  • Communication distance: Here, we will use the iPhone 6 as an example. In an indoor environment without any obstructions, for the 5-GHz Wi-Fi band, the communication distance is between 8 to 12 meters at full negotiation speed and the connection can be maintained at 70 to 90 meters.
  • Select a proper location: If possible, install the routers on the ceiling or a desktop. This not only ensures the coverage quality but also saves floor space. To improve the aesthetics of the router, you can purchase a router that conforms to your decor or paint it yourself.
  • Improve network ports: To make the full-strength Wi-Fi signal available at all locations, you must deploy wired ports in each room. The wireless network can be expanded by using a wireless bridge, but this will significantly reduce the communication quality.
  • Reduce the number of devices: Generally, the more wireless routers you have, the higher the probability of terminal roaming, disconnection, and reconnection. In addition, the probability of protocol conflicts, such as DHCP coverage conflicts and same-frequency interference, and the complexity of the network architecture also increase. Therefore, you need to reduce the number of devices as much as possible.
  • Wireless relay: In large houses without weak current network ports in each area, to reduce the construction work required and the visual impact, you can use a “bridge relay” or a MESH-based deployment solution. However, using a relay MESH solution where a wireless bridge is used for interconnection will negatively affect the final user experience. The reason is easy to understand. Each connection causes bandwidth loss and ultimately reduces the overall bandwidth. For each hop of the bridge, the bandwidth is reduced by half. Therefore, we recommend you only use one level of sub-routers.
  • Power Line Communication (PLC) modems: In large houses without weak current network ports in each area, to reduce the required construction work, you can also use PLC modems, which are a powerful tool. Using frequency division technology, the PLC modem transforms normal electrical wires into communication lines. You can deploy a PLC modem to extend the communications network along an electrical wire system in the area of a single electrical meter. However, in terms of electromagnetic characteristics, electric wires are not optimized for high-frequency signal transmission and cannot be compared with dedicated communication cables such as optical cables, twisted pairs, and coaxial cables. Electric wires have the disadvantages of high interference and poor signal integrity and are vulnerable to high current fluctuations during peak power consumption hours or due to unstable voltage. Therefore, this solution has inherent defects in communication quality and stability and many fault points. If you have high requirements for network stability, we do not recommend this method.
  • Band selection: The 2.4-GHz band has good penetration, but only three channels are available, as shown in the following figure. Compared with the 5-GHz band, the 2.4-GHz band has a narrow bandwidth, with low speed and high interference. We recommend that you use this band for smart home, IoT devices, and guests, and configure a separate Service Set Identifier (SSID) and security policy for it.
  • Channel binding: A wider channel bandwidth provides a higher communication bandwidth. Generally, the bandwidth of Intel 802.11 AC network cards for laptops is 20 MHz (173 Mbit/s), 40 MHz (400 Mbit/s), or 80 MHz (866Mbit/s). However, a wider channel is more vulnerable to interference and has greater latency. Therefore, we recommend the 40 MHz bandwidth instead of the 20 MHz or 80 MHz bandwidth. This is shown in the following figure:
  • Channel selection: Use the tool software — the specific software name is mentioned below — to scan idle channels and configure the wireless router to use such a channel. Each router in the home must be set to different channels to avoid same-frequency interference.

Network Optimization Methods

Wi-Fi Locations and Spectrum Design for Different Apartment Types

  • Small Apartments
  • Medium-sized Apartments
  • Large Apartments
  • Houses (consider each floor as a corresponding apartment type)

Network Architecture Design

Architecture Related Questions

  • We use 100 Mbit/s ADSL bandwidth in our home. Why doesn’t the tested bandwidth on our computers and mobile phones reach 100 Mbit/s?
  • Outbound bandwidth calculation: The outbound bandwidth is calculated based on the total concurrent peak traffic of all terminals in the home during a certain time window. Usually, the traffic of HDTV sets is about 4 Mbyte/s, that of ordinary computer video services is 2 Mbyte/s, and that of mobile video services is usually 1 Mbyte/s. During P2P downloading and uploading, the traffic is based on application requirements.
  • Key access resources: Access to popular websites and apps is ensured by networks of the three major carriers in China. Check the situation in your local country. If you have special requirements, for example, if you need to communicate a home in another city through a high-traffic video stream, you can select the carrier with the lowest number of hops to the target IP address. To trace the number of hops and latency, you can run the tracert x.x.x.x command.
  • My network disconnects frequently, and some devices cannot access the Internet. Why is an exclamation mark displayed in the network connection icon on my terminal?

Security-Related Questions

  • How can I make sure that I have good network security?
  • Common protection: The CIDR blocks of the Wi-Fi for family members and the Wi-Fi for guests are different and routes of core devices are isolated. WPA2 AES CCMP is configured for strong encryption and the password is regularly updated.
  • Moderate protection: We recommend that you mask the household Wi-Fi SSID. Technically, the SSID name can be captured by capturing packets. Therefore, you need to add matching policies. You can configure WPA2 AES CCMP for strong encryption, disable DHCP, enable static address allocation, add MAC address binding, restrict MAC access, and implement other policies individually or in combination.
  • Strict protection: In addition to the measures in the preceding two modes, you can purchase firewalls at different levels, strictly design inbound and outbound data traffic policies, and strictly protect the security of all devices and systems in your home. For example, you can regularly update the software of router devices and access point devices to remove software security and functional vulnerabilities.
  • My Wi-Fi password is quite complex and I can’t remember it myself. How did someone else crack it? What should I do?

Router and Other Device Related Questions

  • What devices, including wireless routers, should I purchase for my home?
  • Why are some household wireless routers more expensive and others less expensive?
  • What is the most practical way to strengthen my Wi-Fi signal?
  • Is it better to have more antennas? Do more antennas give you better wall penetration?
  • How should I use a Wi-Fi bridge to cover a large apartment?

Performance Testing

  • Test tool: For PCs, you can use Inssider, WirelessMon, or Wireless Netview based on your system.
  • Test method: Use the preceding tool software to test the signal and bandwidth in the target coverage area, ping the gateway, and browse some major websites.
  • Indicators: In the target coverage area, the received signal strength is greater than or equal to -75 dBm, and in areas with voice and video services, the received signal strength is greater than or equal to -67 dBm.

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