Broadband technology competition
What is WiMAX technology?
WiMAX (Worldwide Interoperability for Microwave Access) Microwave Access Global Interoperability Certification Industry Alliance The main members include equipment manufacturers, device suppliers, operators, etc. The main task is to eliminate IEEE802 by performing product compatibility and interoperability certification .16 Obstacles to the application of standards, expand the scope of application of standards. 802.16 is a wireless access technology air interface standard developed by IEEE802. Representative standards include 802.16d fixed wireless access and 802.16e mobile wireless access standards. According to the current technological development, 802.16d is mainly targeted at enterprise users, providing a means of long-distance transmission, while the user group of 802.16e is positioned at individual users, supporting users to access the broadband network in a mobile state.
WiMAX is an emerging technology that can provide "last mile" broadband connectivity in a wider geographic area than Wi-Fi, thereby supporting corporate customers to enjoy T1 services and residential users have access equivalent to cable / DSL ability. With its 1 to 6 mile coverage in any location (depending on various factors), WiMAX will provide better mobility for high-speed data applications. In addition, with this coverage and high throughput, WiMAX can also provide backhaul for telecommunications infrastructure, enterprise parks, and Wi-Fi hotspots.
WiMAX will be deployed in three stages. The first stage is to deploy WiMAX technology using the IEEE 802.16d specification through indoor antennas. The target users are known subscribers at fixed locations. In the second phase, a large number of indoor antennas will be deployed to broaden the appeal of WiMAX technology to operators seeking to simplify the installation of user sites. The third phase will introduce the IEEE802.16e specification. In this specification, WiMAX certified hardware will be applied to portable solutions for users who want to roam in the service area. It supports a connection that is similar to today ’s Wi-Fi capabilities, but more durable and stable. Sex.
The primary challenges facing WiMAX are still its construction costs and equipment prices. The current MMDS multi-point multi-channel distributed system, the cost of each user including WiMAX antenna deployment is up to about 3,000 US dollars, which not only makes it difficult for operators to obtain sufficient return on investment, but also makes users daunted and retreat, let alone China The 3.5GHz frequency band is a very limited MMDS broadband wireless access system. After several rounds of program updates and technological innovations, various types of equipment have already had a very good price-performance ratio. WiMAX will face severe challenges if it participates in competition at similar prices as mentioned above . In addition, WiMAX, Wi-Fi, and 3G will complement each other for a long time, and will compete with each other to a certain extent in the overlapping area. To this end, maintaining effective interconnection between these system applications and enhancing their own competitiveness are also It is an important task facing WiMAX.
WiMAX to 3G
3G is an ITU specification that supports high-speed wireless communications. This worldwide wireless connection is compatible with GSM, TDMA and CDMA. The next generation of 3G cellular services can provide a remote wireless access range for voice and data. Operators around the world are currently deploying 3G network infrastructure for towns, suburbs, and rural areas with heavy traffic. The next generation of 3G cellular services can create a wide range of data access across multiple geographies, thereby providing the most ideal mobile computing capabilities for voice communications and Internet connections.
Since its introduction, IEEE802.16e has attracted more attention, especially driven by industry giants such as Intel and the WiMAX organization. The industry has launched a heated discussion on 802.16e, especially the relationship between 802.16e and 3G, there are many different Views: Some believe that 802.16e will replace 3G, while others believe that 802.16e is unlikely to replace 3G, but is a complementary technology to 3G. In order to analyze the relationship between 802.16e and 3G, the following comprehensive comparison of these two technologies.
For 802.16e technology and 3G technology, first of all, due to the different positioning, there is a big difference between the two.
From the perspective of standardization, 802.16e only defines the physical layer and MAC layer of the air interface. The protocol and core network part adopted above the MAC layer are not included in the scope of 802.16e. The air interface standardization of 802.16e is expected to be completed in the near future. As a complete network, 3G technology has completed standardization of air interface specifications, core network series specifications, and service specifications, involving wireless transmission, mobility management, business applications, and user number management.
In terms of service capabilities, 802.16e mainly provides broadband data services with certain mobile characteristics, and the users are mainly notebook terminals and 802.16e terminal holders. 802.16e accesses the IP core network and can also provide VoIP services. From the beginning, 3G was designed for voice services and data services. For voice services, the core network is still implemented by circuit switching, and QoS is guaranteed. 802.16e sacrifices mobility in exchange for the improvement of data transmission capabilities, and its data bandwidth is superior to 3G systems. However, the data capacity of 3G is also constantly improving. 3G enhanced types such as HSDPA can already achieve an access rate of 10 Mbit / s. According to ITU's definition, the ultimate goal of 3G enhanced can reach 30Mbit / s.
Although the transmission rate of WiMAX can reach 10 times or more of 3G, and its coverage can be matched with or even further away from 3G when using low-order modulation, but this is not a 3G standard. It uses wireless WAN WWAN as the basic mode, and uses public voice and multimedia data For the basic market positioning of personal mobile terminals roaming around the world, WiMAX is essentially an important support method for 3G and 3G evolution as a wireless metropolitan area network and multi-point base station interconnection. The potential market size of the two There are also huge differences, making it impossible to say that WiMAX will become the terminator of 3G.
From the perspective of coverage, in order to obtain higher data access bandwidth (30Mbit / s), 802.16e must sacrifice coverage and mobility. Therefore, 802.16e will mainly solve hotspot coverage in a long time, and the network can provide some For mobility, the main application will focus on data access in nomadic or low-speed mobile states. 3G is a ubiquitous network with continuous coverage, and users can achieve uninterrupted communication.
From the perspective of wireless spectrum resources, 3G has a unified global spectrum resource, and 802.16e is trying to find frequency resources between 2 and 6GHZ. The frequencies currently available in various countries are inconsistent. Therefore, it is difficult for 802.16e to finally obtain sufficient global uniform frequency.
From the analysis of the above perspectives, it can be seen that although 802.16e is superior to 3G in data capabilities, from the perspective of standardization, global unified spectrum, and technical characteristics, 802.16e still has a long way to go before it is truly commercial. And, in a long time, it mainly solves hot spot coverage and solves some mobility. Its application will be after 3G. The emergence of 802.16e will not affect the development of China's 3G industry.
WiMAX to Wi-Fi
Wi-Fi is an abbreviation of Wireless Fidelity. Wi-Fi technology includes the IEEE802.11a, b, and g specifications that have been approved and the 802.11n specifications that are pending approval. Wi-Fi is the first widely deployed high-speed wireless technology, which is particularly noticeable among global hotspots-including homes and offices as well as more and more coffee houses, hotels and airports, and Wi-Fi hotspots are almost immediate Popular in the world, and because of its ability to improve work efficiency, it is sought after by people who travel abroad. However, the range that Wi-Fi can support is very limited: users can only achieve high-speed connections by staying within 300 feet of the wireless access point device (AP). Wi-Fi is one of the earliest high-speed wireless data technologies, and now it has gained a lot because of the large number of supporting products and technologies. Some of the latest platforms can even support multiple Wi-Fi standards (such as 802.11a, b, and g) to support compatibility between several wireless networks.
Wi-Fi has set off a strong boom in the market in recent years. In 2002, a total of 18 million Wi-Fi "hot spots" were sold worldwide, and telecom operators in various countries were scrambling to join the Wi-Fi camp. It is predicted that by 2007 there will be 530,000 hotspots in the US, 700,000 in Europe, and more than 1 million hotspots in Asia. Why is Wi-Fi developing so quickly?
Wi-Fi has the reputation of "wireless version of Ethernet". Since the current Ethernet standard (IEEE 802.3 standard) has almost become synonymous with LAN, at least 80% of LANs in the world use Ethernet technology. And WLAN is also a standard formulated by IEEE, so it can almost be regarded as an extension of the Ethernet standard in the wireless field. This makes WLAN has the characteristics of seamless and smooth installation.
The installation and setup of WLAN is quite simple-when you need to establish a network connection in a certain area, you only need to set up the corresponding access point within a certain range, and the traditional procedures such as planning, wiring, and testing can be ignored. And the operation when the user needs to add, remove and relocate is also very simple. If deploying a LAN in an Internet cafe, it will take a lot of time in HUB, cable layout, etc., and after the introduction of Wi-Fi at home, the entire access process is less than 10 minutes.
The overall cost of WLAN is very low. It is reported that through the implementation of wireless LAN solutions, enterprises with an average user size of 400 points can save up to 4.9 million US dollars in networking costs. Due to the convenient access, low cost and no need to apply for a license, WLAN is in the field of public access services Become a star.
The bandwidth of 802.11b can reach 11Mbit / s, while 802.11a and 802.11g can reach 54Mbit / s. Such a high bandwidth almost catches up with the connection of cables, greatly surpassing the same type of wireless network technology. At the same time, in addition to the network, the application of WLAN will be expanded to a wider range, in addition to integration in notebook computers, PDAs, mobile phones and other devices, it will also be integrated into products such as printers, DVD players, game consoles, MP3, etc. Its function will be further enhanced.
Although Wi-Fi has many advantages, its potential security risks are a fatal flaw. Wi-Fi uses radio frequency (RF) technology to send and receive data over the air. Because wireless networks use radio waves to transmit data signals, they are very vulnerable to attacks from outside. Radio waves can penetrate walls and partitions, and hackers can easily steal data within the coverage of radio waves and even enter unprotected companies. Internal LAN.
However, although the rise of Wi-Fi is rapid, in the face of the aggressive development of WiMAX, there is public opinion that WiMAX will replace Wi-Fi, but some people think that WiMAX will not replace Wi-Fi, and both sides will complement each other in wireless access. The most obvious difference between WiMAX and Wi-Fi is that there is a huge difference in coverage. Wi-Fi can only reach a maximum coverage of 300 feet, but can only be used in a wireless LAN environment, while WiMAX 802.16e can usually reach 1 to 3 miles , Mainly positioned for use in mobile wireless metropolitan area network environments.
WiMAX to DSL
According to whether the upstream and downstream rates are the same, xDSL technology can be divided into two types: rate symmetric and rate asymmetric. Rate symmetrical xDSL has various forms such as IDSL, HDSL, SDSL (Single line DSL), HDSL2, etc. Asymmetrical xDSL includes ADSL (Asymmetric DSL), G.lite ADSL and VDSL (Very high bit rate DSL). At present, the most widely used is ADSL technology.
ADSL is a new technology that simultaneously transmits telephone service and data signals on a pair of twisted pairs. It belongs to the rate asymmetric copper wire access network technology, and can carry up to 640Kbit / s on a pair of subscriber lines. , Downlink transmission up to 1.5 ~ 8Mbit / s. In addition, ADSL uses advanced digital signal processing technology to reduce the impact of line damage on transmission performance.
Although ADSL uses advanced digital signal processing technology, code modulation technology and error correction technology, when promoting ADSL services, many characteristics of subscriber lines include background noise, impulse noise, line insertion loss, and crosstalk between lines Factors such as wire diameter changes, line bridge taps, line connectors and line insulation will affect the performance of high-speed transmission services.
HDSL is one of the more mature DSL technologies at present. Its characteristic is to use two pairs of twisted pairs to realize data transmission. It supports various rates of N × 64Kbit / s, and the highest bidirectional rate is 2Mbit / s. HDSL can achieve normal data transmission within 3.6 kilometers without the aid of relay amplifiers. Compared with the traditional T1 / E1 technology, the most prominent advantage of HDSL is its low cost and easy installation. It is one of the ideal alternative technologies for the digital trunk interface T1 / E1. SHDSL is an upgrade technology of HDSL (High Bit Rate DSL) single-line version, that is to say, it can save a pair of twisted pairs, the transmission rate is faster, the transmission distance is farther, so the installation is more convenient. SHDSL can provide 2.3Mbit / s bandwidth for both upstream and downstream to meet the special needs of business users. More market value is that the compatibility of SHDSL equipment and ADSL equipment can enable different equipment to provide different services on the same platform, reducing the equipment investment and installation costs that operators add to the existing ADSL system. Telecom operators using SHDSL technology can provide users with cheap and convenient dedicated line services, and improve the competitiveness of using DSL technology in the broadband access market.
VDSL technology advances the transmission rate of twisted pair to a very high level. VDSL requires a very high data transmission rate over a relatively short distance, with a maximum transmission rate of 58 Mbit / s. From a technical point of view, VDSL can actually be regarded as the next-generation technology of ADSL, and its average transmission rate can be 5 to 10 times higher than that of ADSL. VDSL can use symmetric and asymmetric transmission methods, and supports ATM and STM transmission, providing voice and video conferences and digital images. For telecom operators, VDSL is the best solution to enter video services. As the ultimate technology of DSL technology, VDSL does have an unparalleled advantage in access rate, especially the use of the now laid telephone line as a transmission medium.
Comparing WiMAX technology and DSL technology, each has its own advantages. In terms of usage environment, WiMAX technology is used for wireless access and DSL technology is used for wired access. It is inevitable that WiMAX technology has greater flexibility than DSL technology in networking applications. In terms of transmission rate, the maximum speed of WiMAX technology can reach 30Mbit / s, and the theoretical maximum speed of DSL technology can reach 58Mbit / s, but DSL is more susceptible to the characteristics of subscriber lines, and the actual speed may decrease. In terms of coverage, WiMAX can reach up to 6 miles, while DSL can only cover 3.6 kilometers (2.2356 miles). Although DSL technology has obvious disadvantages compared to WiMAX technology, DSL technology is based on the existing copper wire, and the cost is significantly lower than WiMAX. However, as time goes by, once the development of WiMAX technology makes the cost large Decline in magnitude, DSL technology will face the threat of being eliminated by WiMAX technology.
WiMAX to Cable
Cable Modem technology can be divided into two-way symmetric transmission and asymmetric transmission from the transmission mode. The symmetrical transmission rate is 2Mbit / s ~ 4Mbit / s, the highest can reach 10Mbit / s. The asymmetric transmission downlink rate is 51 Mbit / s, and the uplink rate is 500 Kbit / s to 31 Mbit / s. Cable Modem itself is not just a modem, it combines the functions of Modem, tuner, encryption / decryption device, bridge, network interface card, virtual private network agent and Ethernet hub. It does not require dial-up Internet access, does not occupy telephone lines, and can provide a permanent connection online at any time. A virtual private network connection is established between the service provider's equipment and the user's Modem. Cable Modem provides a standard 10BaseT or 10 / 100BaseT Ethernet interface to connect with the user's PC equipment or Ethernet hub. The technical realization of Cable Modem is generally to separate a 6MHz channel from 42MHz to 750MHz TV channel for downlink data transmission. Usually the downstream data adopts 64QAM (quadrature amplitude modulation) modulation method, the highest rate can reach 27Mbit / s, if adopt 256QAM, the highest rate can reach 51Mbit / s.
In the Cable Modem system, a two-way asymmetric technology is used, and there is a 6MHz analog bandwidth in the downstream direction for users in the system to share. But this sharing technology will not reduce the transmission rate. Cable Modem is different from the directional call connection of the line-switched telephone network. Users do not occupy a fixed bandwidth when connecting, but share it with other active users and use network resources only at the moment of sending and receiving data. In the time of milliseconds or even microseconds, seize all opportunities to use bandwidth to download data packets. If there is congestion during the peak period of network usage, it can be solved by flexibly allocating additional bandwidth. Simply allocate a 6MHz frequency band to double the downlink speed. Another method is to re-divide the physical network in the user segment, and allocate bandwidth to users reasonably according to the frequency of access. The speed is comparable to that of the dedicated line.
The use of Cable Modem and HFC for networking has some problems in stability, reliability, power supply, and operation and maintenance systems. Although the theoretical rate of Cable reaches 51Mbit / s, because the cable line bandwidth is shared, the broadband data service cannot be provided after the user reaches a certain scale, and the bandwidth shared by the user is very limited. WiMAX technology relatively speaking, the advantage of bandwidth is more obvious.
Because all signals of Cable Modem users are transmitted on the same coaxial cable, there is a risk of wiretapping. The CATV's tree-like network characteristics also lead to a single point of failure, such as cable damage, amplifier failure, transmitter failure will cause the interruption of user services on the entire node. Although the early users of Cable Modem can certainly enjoy very high-quality services, because the bandwidth and frequency band of the line are very abundant when the number of users is small. However, the addition of each Cable Modem user will increase noise, occupy channels, reduce reliability, and affect the existing user service quality on the line. WiMAX technology does not have these concerns, and security and stability are well guaranteed.
In addition, considering the cost of networking, Cable Modem can only be applied after the HFC transformation is completed. At present, most HFCs in our country can only meet the 450MHz frequency band requirements, and the use of HFC to provide bidirectional services requires at least 750MHz bandwidth. This obviously requires replacing all coaxial cables that do not meet the requirements. At the same time, to achieve bidirectional HFC, it is necessary to replace the unidirectional amplifier currently used on the cable TV network, and the high cost of reconstruction also makes Cable technology difficult to compete with WiMAX technology.
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