标签：Chapter Lectures Networking network wireless host station base networks

Computer Networking:

a Top-Down Approach (8th ed.):

Notes of "Select" Lectures

 

7.1 Introduction

Elements in a wireless network

•    Wireless hosts.

•    A wireless host (无线主机) might be a smartphone, tablet, or laptop, or it could be an Internet of Things (IoT) device.

•    The hosts themselves may or may not be mobile.

•     Wireless links.

•    A host connects to a base station or to another wireless host through a wireless communication link (无线通信链路).

•    Different wireless link technologies have different transmission rates and can transmit over different distances.

•    Base station.

•    The base station (基站) is a key part of the wireless network infrastructure.

•    A base station is responsible for sending and receiving data (e.g., packets) to and from a wireless host that is associated with that base station.

•     "associated":

• the host is within the wireless communication distance of the base station

• the host uses that base station to relay data between it and the larger network. Examples:

•    cell towers (蜂窝塔) in cellular networks

•    access points (接入点) in 802.11 wireless LANs

•    Hosts associated with a base station: operating in infrastructure mode (基础设施模式)

•    since all traditional network services are provided by the network to which a host is connected via the base station.

•    In ad hoc networks (自组织网络), no such infrastructure. The hosts themselves must provide for services.

•    Handoff (切换) or handover (切换):

• When a mobile host moves beyond the range of one base station and into the range of another, it will change its point of attachment into the larger network.

•    Network infrastructure. This is the larger network with which a wireless host may wish to communicate.

Taxonomy (分类学) of different types of wireless networks

    Two criteria:
(i) one wireless hop or multiple wireless hops
(ii) infrastructure.

•    Single-hop, infrastructure-based.

•    A base station is connected to a larger wired network (e.g., the Internet).

•    All communication is between this base station and a wireless host over a single wireless hop.

•    802.11 networks; 4G LTE data networks. The vast majority of our daily interactions are with them.

•    Single-hop, infrastructure-less.

•    No base station is connected to a wireless network.

•    One node may coordinate the transmissions of the others.

•    Bluetooth networks.

•    Multi-hop, infrastructure-based.

•    A base station is present that is wired to the larger network.

•    Some nodes may have to relay in order to communicate via the base station.

•    Some wireless sensor networks; wireless mesh networks (无线网状网络).

•    Multi-hop, infrastructure-less.

•    No base station.

•    Nodes may have to relay to reach a destination.

•    Mobile ad hoc networks (MANETs, 移动自组织网络); vehicular ad hoc network (VANET, 车载自组织网络).

标签：Chapter,Lectures,Networking,network,wireless,host,station,base,networks
来源： https://www.cnblogs.com/zjnu/p/kurose_ross_7.html

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