无线通信缩写词WIN(Wireless Intelligent Network)的含义是()。
A.无线智能网
B.局域网
C.广地网
D.无线城域网
A.无线智能网
B.局域网
C.广地网
D.无线城域网
Beijing 2008: The First 4G Wireless Olympic Games ?
About half a million years ago, Peking man lived in Zhoukoudian, in the southwestern suburbs of what is now Beijing. If you have been to Beijing more recently, or are at all familiar with modern China, then you know this ancient city is going to host the most modern, high-tech Olympic Games ever in 2008. With technology available today, and a vision for what Beijing could be in 2008, there is an opportunity for the hosts to make the city's telecommunications infrastructure--in the words of the Olympic motto — "swifter, higher, stronger". The Path to 4G
Beijing has the good fortune of looking at previous generations of wireless networks and avoiding the same mistakes as it prepares for 2008. First Generation (1G) wireless telecommunications — the brick-like analog phones that are now collector's items—introduced the cellular architecture that is still being offered by most wireless companies today. Second Generation (2G) wireless supported more users within a cell by using digital technology, which allowed many callers to use the same multiplexed channel. But 2G was still primarily meant for voice communications, not data, except some very low data-rate features, like Short Messaging Service (SMS). So-called 2.5G allowed carriers to increase data rates with a software upgrade at the base transceivers Stations (BTS), as long as consumers purchased new phones too. Third Generation (3G) wireless offers the promise of greater bandwidth, basically bigger data pipes to users, which will allow them to send and receive more information.
All of these architectures, however, are still cellular. Cellular architecture is sometimes referred to as a "star architecture', because users within that cell access a common, centralized base station. The advantage is that given enough time and money, carriers can build nationwide networks, which most of the big carriers have done. Some of the disadvantages include a singular point of failure, no lead balancing, and spectral inefficiencies. The single biggest disadvantage to cellular networks going forward is that as data rates increase, output power will have to increase—or the size of the cells win have to decrease—to support those higher data rates. Since significant increases in output power scare both consumers and regulators, it is far more likely that we will see significantly smaller cells. This will further reduce the return on investment in already fragile 3G business plans.
Fourth Generation (4G) wireless was originally conceived by the Defense Advanced Research projects Agency (DARPA), the same organization that developed the wired Internet. It is not surprising, then, that DARPA chose the same distributed architecture for the wireless Internet that had proven so successful in the wired Internet. Although experts and policymakers have yet to agree on all the aspects of 4G wireless, two characteristics have emerged as all but certain components of 4G:end-to-end Internet Protocol (IP) ,and peer-to-peer(点对点)networking. An all IP network makes sense because consumers will want to use the same data applications they are used to in wired networks. Peer-to-peer networks, where every device is both a transceiver (收发机) and a router (路由器) for other devices in the network, eliminates the weakness of cellular architectures, because the elimination of a single node does not disable the network. The final definition of "4G" will have to include something as simple as this: if a consumer can do it at home or in the office while wired to the Internet, that consumer must be able to do it wirelessly in a fully mobile environment.
Let's define "4G" as "wireless collaborated peer-to-peer networking". 4G technology is significant because users joining the network add mobile routers to the network infrastructure. Because users carry much of the network with them, network capacity