802.16e

802.16e IEEE 802.16e mobile broadband wireless access standard that is backward compatible IEEE 802.16d. IEEE 802.16e physical layer implementation is consistent with the IEEE 802.16d, the main difference is the OFDMA has been extended to support the 2048-Point ,1024-Point ,512-Point and 128 - Point, in order to adapt to different carrier bandwidths needs. In order to support mobility, 802.16e MAC layer introduces many new features. Wireless access technology trends through the introduction of new technologies (OFDM, MIMO, etc.) to achieve higher capacity, greater coverage and achieve a certain degree of mobility, and 3G networks co-exist and complement each other. Therefore, 802.16e technology emerged from an industry has become the focus. The objectives set by IEEE 802.16e, the system has the following basic features: (1) high-speed mobile 802.16e can support both fixed (16d) and mobile (16e) wireless access, the speed of its moving rate target for the Mobile (usually that can reach 120km / h). (2) broadband access System at different carrier bandwidths and modulation mode, you can get different access rates. The 10MHz carrier bandwidth, for example, the use of OFDM-64QAM modulation to remove the overhead, the single-carrier bandwidth of about 30Mbit / s access rates effective from cellular or shared by all users within the sector. IEEE 802.16 standard does not provide the carrier bandwidth for carrier bandwidths ranging from 1.75MHz to 20MHz, the nominal maximum bandwidth 70Mbit / s is under certain conditions can be achieved. (3) metro coverage 802.16e base station coverage in a single order of a few km, used in the metropolitan area. (4) Main business 802.16e system will provide data access to IP-based core network, mainly for individual users to provide data access services, can also provide voice services.
 802.16e wireless access technology, from a technical point of view, as the technology matures, may experience different stages of development: (1) 802.16d base station and terminal maturation, 802.16d network deployment, 802.16d gradual development from outside the terminal to the interior. (2) 802.16e networks beginning to deploy, 802.16e portable terminal there, but the initial was "hot spot" coverage, can not support the switch move, but can support the roaming mobile. (3) 802.16e network from point to surface, and gradually scale coverage, and ultimately support the switch move.
 802.16e supports mobility, it is an unavoidable problem with the relationship between 3G, the following is from a technical point of view of 3G and 802.16e compared.
 802.16e: Fixed or have a certain mobility of users, requires a certain mobility of broadband data services; users in a certain area of ​​mobility and roaming.
 To broadband data services based (business is not within the scope of 802.16e) Packet-based structure. Currently the network includes only wireless access network. Can support the 120km / h mobile speed
 Can support more than 120km / h mobile speed With the existing 2G mobile communication network is not compatible 3G: Higher rate of mobile users, the need for voice services and data services; 3G enhanced data rates for high-speed downlink required services; support full mobility and roaming.
 Provide circuit-based voice services, circuit-and packet-based data bearer; provide video telephony (circuit-or packet-based), multimedia message service, location service, short message service, etc.; to provide IP-layer access. Type of circuit and packet-based structure, the structure co-exist, and to the evolution of packet-based network structure. Network, including wireless-based core network and the type of packet-based core network, as well as in business-related subsystems (such as positioning systems, etc.).
 Can support more than 120km / h mobile speed.
 With the existing 2G mobile communications network for the evolution of relations between relations.
 All in all, from the positioning of the business can be concluded that, 802.16e and 3G systems positioned in a particular range of memory in the overlap, this overlap is present mainly in the "demand for higher data bandwidth to provide a mobile urban areas of wireless data services "as well. 802.16e and 3G systems in the wireless transmission technology than in the provision of broadband wireless data services technical advantage is certain, the technology has a competitive advantage. 802.16e mobile at the same rate can provide data rates higher than the 3G systems, enhanced systems and 3G (HSDPA and 1x EV-DV) the current target. But in the relevant standards and product maturity and the degree of industrialization and other aspects, 802.16e behind the 3G system. 802.16e impact on the 3G system can be divided into two phases, in the 802.16e achieve commercial level, it will not on China's impact on the development of 3G systems, but will be the concern of operators and equipment manufacturers of domestic R & D investment. When 802.16e developing smoothly, to business, you will be in the wireless broadband data services and 3G systems within a certain range of competitive and complementary situation. While the future development of 802.16e, but also take into account the mobile operator's network at the situation and development strategies, industry size and equipment costs, government policies, spectrum allocation and other factors, these factors are not yet clear, but they are the future need for further consideration and study.