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What is a Reliable Wireless Network? - Definition & Factors

Instructor: Noemy Alcauter

Mayra has a BA in Technology Education and has worked as a content creator and curriculum developer for computer science and coding subjects in e-learning platforms.

This lesson describes wireless networks and the usual causes of signal interference that result in network unreliability. It focuses on how TCP/IP breaks data into packets to ensure that it is sent and received reliably from one device to another.

Reliable Wireless Network

A wireless network uses radio frequency technology to send and receive data, with no need for cables. A wireless network can sometimes suffer signal interference, which weakens radio signals and affects the overall performance when transferring data. Some of the most common factors that can cause unreliability are:

  1. Obstructions, such as large buildings or trees
  2. Environmental factors, such as fog, rain, lightning, and weather
  3. Distance between devices
  4. Wireless network interference, where many devices are sending signals on a particular frequency simultaneously
  5. Other electronic devices, such as refrigerators, wireless phones, and microwaves

Fortunately, all networks can avoid and cope with failure. A reliable network has the ability to perform a set of functions under determined conditions for specified operational times.

Packets

Imagine you bought a table through an online store, but the furniture store sends each piece to you in separate boxes by postal service. You might receive each box at different times, but once you have them all, you will build your new table. But what if one of those boxes gets lost in its journey? Assembling the table will be impossible! Well, this is how data is sent and received through the Internet.

The internet's infrastructure has physical limitations, such as how large a message sent from one device to another can be. Every time you send and receive data through the Internet, it is divided into separately numbered packets that are sent at specific time intervals to ensure reliability.

While packets travel separately through the internet, there's a lot that can go wrong. For instance, packets can be lost, which is a big problem considering that a message needs all its packets to be put together. Also, packets can arrive out of order, and multiple messages may be sent to a single device, which will need to identify which packet belongs to each message.

Packet loss is not uncommon; losing one or two of them doesn't mean a problem has occurred. However, the more losses there are, the more repeated transmissions must be sent, causing network congestion. Packet loss may have many causes, such as faults in the infrastructure or corruption of the header information.

Here are some causes of packet loss:

  • The software in use is invalid or has an excessive number of bugs.
  • Inconsistent jitter, or delay inconsistencies, makes timing an issue on the receiving end.
  • An unstable connection may be caused by any of the previously mentioned factors of interference.
  • Slow network speed delivers packets inconsistently.

So, how can a network assure all packets have been sent and received at their destination? This is where TCP/IP is in charge.

TCP/IP

TCP/IP provides end-to-end communication and decides how data should be broken down into packets, addressed, transmitted, routed and finally, received at the destination. It is designed to make networks reliable, so it notifies the user if delivery fails. Each part of this protocol performs specific functions.

TCP

The Transmission Control Protocol delivers reliability with PAR, which stands for Positive Acknowledgment with Retransmission. When a system uses PAR, it will send packets as many times necessary, until it receives information from the remote system stating that the data has arrived with no problem.

But, how does it know that the data has been received correctly? A checksum is used to detect errors that may have been introduced during transmission. It's something each packet contains. It works by helping the recipient verify the data is undamaged; if it is undamaged, the receiver will send a positive acknowledgment to the sender. However, if data happens to be damaged, the receiver will discard it. After a while, the TCP module will re-transmit the packets that did not send back a positive acknowledgment.

When the TCP host wants to set connections between two endpoints, it exchanges control information in a three-way handshake:

  1. TCP sends a message called a SYN (short for synchronize).
  2. The server that receives it returns an ACK (short for acknowledge).
  3. A link between both systems has been established.
  4. The data is transferred.
  5. A three-way handshake is exchanged containing a FIN bit, which confirms that there is no more data from the sender.
  6. The connection is closed.

TCP packets turn to several mechanisms to ensure connection state, reliability and flow control of data:

  1. Streams: Data is arranged as a flow of bytes.
  2. Reliable delivery: TCP coordinates the way data is received and delivered by using sequenced numbers.
  3. Network adaptation: TCP learns the characteristics of delays in the network, and modifies its behavior to increase throughput without overloading it.
  4. Flow control: TCP runs data buffers and synchronizes traffic so that the buffers don't overflow.
  5. Round-trip time estimation: TCP records the exchange of data packets, estimates how long it could take to receive an acknowledgment, and automatically retransmits if it exceeds the time.

IP

The Internet Protocol determines how each packet should be addressed and routed to ensure it is collected at the correct destination.

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