Comparison between ddnleased line and ISDN and wireless spread spectrum network

Disadvantages of renting a post and telecommunications link:
DDN is a public telecommunications network with a large network range and a small impact on geographical conditions. However, with the continuous development of computer network communication technology, all walks of life put forward higher requirements for communication rate bandwidth, especially for Multimedia Image Transmission in the future, the establishment of monitoring system applications, more need for high-bandwidth and high-speed communication lines. However, due to the congestion of high-speed communication ports of Posts and Telecommunications, image transmission over low-speed lines is far from enough, and the ddnleased lines provided by the post and telecommunications system generally have the following shortcomings:

☆Leased line installation costs:
At present, if the ddnleased line is used for image transmission, it requires at least KB of communication bandwidth. However, the rental fee of the 512KDDN or ISDN line is rather expensive for one year. You can purchase two leased lines with 3 m wireless connections) in addition, the rental fee cannot convert the link into your own fixed assets.

☆The line is not under your control and difficult to manage:
DDN and ISDN belong to the management of the Department of Posts and Telecommunications. If any problem occurs, they cannot be recovered on their own, affecting normal business operations; in addition, line interruptions caused by construction and wrong cabling are caused by a wide range of stakeholders, resulting in a long recovery period, seriously affecting normal business operations. In addition, the organizational structure and service efficiency of the Post and Telecommunications Department are not high, and the response speed is slow, making it difficult to meet user needs.

☆The line quality is not guaranteed:
In order to reduce the total cost of investment in line construction, the department of Posts and Telecommunications often uses access devices with poor quality at the end of the user, resulting in many Line Error Codes and high error rates, affecting customers' use.

☆Areas where Cables cannot be laid: areas where Cables cannot be laid, such as mountains, ports, and urban areas.

☆Long leased line erection cycle:
From the local post office application to the actual wiring Unicom, the short period is half a month long then half a year. Therefore, the above analysis shows that the wireless digital communication network is of great significance as a supplement to the high-speed communication line. Advantages of the wireless Spread Spectrum Communication Network.

☆High Network Security:
It ensures data transmission without errors and is confidential and reliable. If the spread spectrum frequency hopping communication technology is adopted, the probability of being captured during information transmission is greatly enhanced.

☆Strong anti-clock performance:
The receiver has the ability to avoid interference with the same frequency of all carriers and the same frequency interference signals entering the receiver. For a spread spectrum frequency-hopping communication system, the signal remains at each frequency for a short period of time, so it has a strong ability to avoid interference between fixed frequency points and local fixed frequency.

☆Strong multi-path fading ability:
Because the PN Codes Used in the Spread Spectrum System have good self-correlation and weak mutual correlation, signals transmitted from different paths can be easily split and re-aligned in time phase, signal Power overlay is formed to improve the performance of the receiving system and increase the reliability of the system. In addition, the spread spectrum communication expands the signal to a wide frequency band, and the fading of some of the signals does not affect the overall reception of the signal.

☆Easy and flexible installation:
You can easily and quickly establish a network without changing the original network structure. Any node on the Internet can be detached from the entire network segment at any time and enter another network, saving the trouble and difficulty of wiring.

☆High communication rate and long distance: generally from 56Kbps-3Mbps. Communication distance up to 30Km

☆The natural environment has little impact on the Spread Spectrum Communication:
Bad weather such as rain, snow, fog, and strong winds has little impact on the Spread Spectrum System. Rain Attenuation, fog attenuation, and other losses can be ignored if the attenuation of spread spectrum communication is less than 0.5dB.

Conclusion: What are the advantages and disadvantages of Wired wireless? It is not difficult to see from the above that the wireless network has the advantages of flexible network construction, convenient and fast network construction, high confidentiality and high reliability, and no need for wiring and other wired networks, however, users should specify which communication network mode should be selected according to the specific situation, in order to achieve the highest performance and price ratio. when wired and wireless networks are combined, all problems may be solved by means of wireless connection. as IT decision makers in the information industry, IT is the most important and perfect choice to make wise choices based on different needs and applications.