https://www.liyitao.cn/category/communication-computer-network/Communication & Computer NetworkWowchemy (https://wowchemy.com)en-usThu, 21 Apr 2022 00:00:00 +0000https://www.liyitao.cn/media/icon_hue23a2bef3590e076477741ababc11dea_177963_512x512_fill_lanczos_center_3.pnghttps://www.liyitao.cn/category/communication-computer-network/https://www.liyitao.cn/post/%E9%80%9A%E4%BF%A1%E4%B8%8E%E8%AE%A1%E7%AE%97%E6%9C%BA%E7%BD%91%E7%BB%9C%E5%9F%BA%E7%A1%80-%E7%BD%91%E7%BB%9C%E4%BC%A0%E6%92%AD%E6%97%B6%E5%BB%B6propagation-delay%E4%B8%8E%E4%BC%A0%E8%BE%93%E6%97%B6%E5%BB%B6transmission-delay/Thu, 21 Apr 2022 00:00:00 +0000https://www.liyitao.cn/post/%E9%80%9A%E4%BF%A1%E4%B8%8E%E8%AE%A1%E7%AE%97%E6%9C%BA%E7%BD%91%E7%BB%9C%E5%9F%BA%E7%A1%80-%E7%BD%91%E7%BB%9C%E4%BC%A0%E6%92%AD%E6%97%B6%E5%BB%B6propagation-delay%E4%B8%8E%E4%BC%A0%E8%BE%93%E6%97%B6%E5%BB%B6transmission-delay/<h2 id="propagation-delay">Propagation delay</h2> <p>The time when data (more specifically, photoelectric signal, because data is hidden in the photoelectric signal during transmission) propagates from one end of the network through the medium to the other end.</p> <h3 id="determinant">Determinant</h3> <p>This mainly depends on the propagation speed of the photoelectric signal in the medium and the length of the direct medium at both ends.</p> <h2 id="transmission-delay">Transmission delay</h2> <p>It may be clearer to change the transmission delay to the transmission delay. <em>Computer Network</em> (the seventh edition, edited by Xie Xiren) is translated as transmission delay, which is easy to be ambiguous for Chinese. The following text also adds a special note to understand it as transmission.</p> <h3 id="determinant-1">Determinant</h3> <p>Actually, it refers to the time required from the start of data transmission to the completion of data transmission. This actually has a great relationship with the channel transmission rate. Note that there is no ambiguity when it comes to speed, and there is ambiguity when it comes to speed.</p> <h2 id="an-analogy-used-to-easily-understand-the-difference-between-the-two">An analogy used to easily understand the difference between the two</h2> <p>Transmission delay is also called transmission delay. The example of a bus can be used for analogy. The transmission delay is similar to that before the bus arrives at the platform, the time spent by the passengers waiting for the bus on the platform from the first boarding to the last boarding is the transmission delay; The time taken by the bus to carry passengers from one station to the next is the propagation delay. In the network structure, the process of sending data to the media is the process of passengers boarding; The time taken for data to propagate on the propagation medium in the form of electromagnetic signals or optical signals is the propagation delay.</p> <h2 id="other-delays">Other delays</h2> <h3 id="queuing-delay">Queuing delay</h3> <p>When a packet is transmitted through a network, it passes through many routers. After entering the router, you should queue in the input queue for processing. After the router determines the forwarding interface, it must queue in the output queue for forwarding</p> <h3 id="nodal-processing-delay">Nodal processing delay</h3> <p>The time generated by the node to store and forward messages (such as parsing messages, looking up routing tables, etc.)</p>https://www.liyitao.cn/post/%E9%80%9A%E4%BF%A1%E4%B8%8E%E8%AE%A1%E7%AE%97%E6%9C%BA%E7%BD%91%E7%BB%9C%E5%9F%BA%E7%A1%80-%E5%8D%95%E8%B7%B3%E4%B8%8E%E5%A4%9A%E8%B7%B3/Thu, 07 Apr 2022 00:00:00 +0000https://www.liyitao.cn/post/%E9%80%9A%E4%BF%A1%E4%B8%8E%E8%AE%A1%E7%AE%97%E6%9C%BA%E7%BD%91%E7%BB%9C%E5%9F%BA%E7%A1%80-%E5%8D%95%E8%B7%B3%E4%B8%8E%E5%A4%9A%E8%B7%B3/<h2 id="definition-of-single-hop">Definition of single-hop</h2> <p>In the traditional wireless LAN, each client accesses the network through an infinite link linked with the AP. If users want to communicate with each other, they must first access a fixed access point. This network is called a <strong>single-hop</strong> network.</p> <h2 id="definition-of-multi-hop">Definition of multi-hop</h2> <p>In a wireless network, any wireless device point can act as an AP and a router at the same time. Each node in the network can send and receive signals, and each node can directly communicate with one or more peer nodes. This network is called a <strong>multi-hop</strong> network. It can also be understood that the transmission of information is completed through forwarding by multiple nodes on the link. Each node can directly communicate with one or more peer nodes. Multi hop means multiple forwarding.</p> <h2 id="concrete-explanation-and-application-of-multi-hop-intermediate-node">Concrete explanation and application of multi-hop intermediate node</h2> <p>In wireless multi hop networks, the typical path from the source node to the destination node is composed of multiple hops, and the intermediate node on the path acts as the forwarding node. Therefore, a node in a wireless multi-hop network has two functions:</p> <ol> <li>Act as an end node to generate or receive data packets;</li> <li>Act as a router to forward data packets from other nodes. The main applications are: wireless AD Hoc network, wireless sensor network (WSN) and wireless mesh network.</li> </ol>