https://leideng.github.io/communication-english/ 通信工程专业英语 Final Review 邓 磊 denglei@dgut.edu.cn https://leideng.github.io/communication-english/ 东莞理工学院 电子工程与智能化学院 2018.11.13/14
Final Exam期末考试 期末考试时间 地点 2018年11月21日（12周周三）晚上19:00-21:00, 6E-306 （课头1）
Outline Lesson 1 Signals: Audio, Image and Video Lesson 2 Systems: Linear versus Nonlinear Lesson 3 Modern Electronic Communication System Lesson 4 Audio Encoding & Video Encoding Lesson 5 Image and Video Compression Lesson 7 Channel Coding: Error Detection & Correction Lesson 8 Analog Modulation and Digital Modulation Lesson 12 Analog-to-Digital Converters (ADC)
Outline Lesson 1 Signals: Audio, Image and Video Lesson 2 Systems: Linear versus Nonlinear Lesson 3 Modern Electronic Communication System Lesson 4 Audio Encoding & Video Encoding Lesson 5 Image and Video Compression Lesson 7 Channel Coding: Error Detection & Correction Lesson 8 Analog Modulation and Digital Modulation Lesson 12 Analog-to-Digital Converters (ADC)
核心词汇 英文 中文 signal sample audio signal magnitude image signal pixel video signal frame function electromagnetic wave electrical light intensity voltage continuous curve waveform discrete-time signal integer grayscale picture
核心词汇 英文 中文 信号 样本 音频信号 幅度 图像信号 像素 视频信号 帧 函数 电磁波 电的 光强度 电压 连续曲线 信号波形 离散时间信号 整数 灰度图像
核心词汇 英文 中文 signal 信号 sample 样本 audio signal 音频信号 magnitude 幅度 image signal 图像信号 pixel 像素 video signal 视频信号 frame 帧 function 函数 electromagnetic wave 电磁波 electrical 电的 light intensity 光强度 voltage 电压 continuous curve 连续曲线 waveform 信号波形 discrete-time signal 离散时间信号 integer 整数 grayscale picture 灰度图像
核心句子 It is customary to normalize the representation of sound by subtracting the ambient air pressure from the range. 从取值范围中减去环境空气压力来归一化声音表示值，这是一种常规做法。
核心句子 For a color picture, the reflected light is sometimes measured in terms of its RGB values (the magnitudes of the red, green, and blue colors). 对于彩色图像，反射光有时可以用RGB值（即红绿蓝的幅度）来度量。
Outline Lesson 1 Signals: Audio, Image and Video Lesson 2 Systems: Linear versus Nonlinear Lesson 3 Modern Electronic Communication System Lesson 4 Audio Encoding & Video Encoding Lesson 5 Image and Video Compression Lesson 7 Channel Coding: Error Detection & Correction Lesson 8 Analog Modulation and Digital Modulation Lesson 12 Analog-to-Digital Converters (ADC)
核心词汇 英文 中文 system phase linear system sinusoid nonlinear system compression encoder bandwidth decoder attenuation codec passband detection transmission medium distortion spectrum component amplitude bandpass filter
核心词汇 英文 中文 系统 相位 线性系统 正弦曲线 非线性系统 压缩 编码器 带宽 解码器 衰减 编解码器 通带 检测 传输介质 失真 频谱分量 振幅 带通滤波器
核心词汇 英文 中文 system 系统 phase 相位 linear system 线性系统 sinusoid 正弦曲线 nonlinear system 非线性系统 compression 压缩 encoder 编码器 bandwidth 带宽 decoder 解码器 attenuation 衰减 codec 编解码器 passband 通带 detection 检测 transmission medium 传输介质 distortion 失真 spectrum component 频谱分量 amplitude 振幅 bandpass filter 带通滤波器
核心句子 A system may enhance a signal by emphasizing some of the information it carries and deemphasizing some other information. 一个系统可以通过增强信号的一些信息和削弱信号的其他一些信息来提高信号的质量。
核心句子 Linear systems can change the time waveform of signals passing through them by altering the amplitude or phase relationships of the spectral components that make up the signal. 通过改变构成信号的各频率分量间的振幅关系或者相位关系，线性系统可以改变信号的时域波形。
Outline Lesson 1 Signals: Audio, Image and Video Lesson 2 Systems: Linear versus Nonlinear Lesson 3 Modern Electronic Communication System Lesson 4 Audio Encoding & Video Encoding Lesson 5 Image and Video Compression Lesson 7 Channel Coding: Error Detection & Correction Lesson 8 Analog Modulation and Digital Modulation Lesson 12 Analog-to-Digital Converters (ADC)
核心词汇 英文 中文 channel acknowledgement switch optical fiber source coaxial cable destination twisted pair synchronous error detection asynchronous TV broadcast overhead RF simplex LAN full/half duplex radar
核心词汇 英文 中文 信道 应答，确认 交换机 光纤 信源 同轴电缆 信宿 双绞线 同步的 错误检测 异步的 电视广播 开销 射频 单工的 局域网 全/半双工的 雷达
核心词汇 英文 中文 channel 信道 acknowledgement 应答，确认 switch 交换机 optical fiber 光纤 source 信源 coaxial cable 同轴电缆 destination 信宿 twisted pair 双绞线 synchronous 同步的 error detection 错误检测 asynchronous 异步的 TV broadcast 电视广播 overhead 开销 RF 射频 simplex 单工的 LAN 局域网 full/half duplex 全/半双工的 radar 雷达
核心句子 Information can be defined as any physical pattern that is meaningful to both sender and receiver. 信息可定义为对发送方和接收方都有意义的物理模式。
核心句子 The telephone itself, of course, is a system. It transforms the electrical signal that propagates down the twisted pair into a sound signal and transforms a local sound signal into an electrical signal that can propagate down the twisted pair. 当然，电话本身也是一个系统。它将传播到双绞线的电信号转换成声音信号，又将本地声音信号转换为可在双绞线上传播的电信号。
Outline Lesson 1 Signals: Audio, Image and Video Lesson 2 Systems: Linear versus Nonlinear Lesson 3 Modern Electronic Communication System Lesson 4 Audio Encoding & Video Encoding Lesson 5 Image and Video Compression Lesson 7 Channel Coding: Error Detection & Correction Lesson 8 Analog Modulation and Digital Modulation Lesson 12 Analog-to-Digital Converters (ADC)
核心词汇 英文 中文 logarithm lower limit quantization linear superposition retina quantization noise intensity ADC luminance DAC chrominance PCM
核心词汇 英文 中文 对数 下限 量化 线性叠加 视网膜 量化噪声 强度 模数转换器 亮度 数模转换器 色度 脉冲编码调制
核心词汇 英文 中文 logarithm 对数 lower limit 下限 quantization 量化 linear superposition 线性叠加 retina 视网膜 quantization noise 量化噪声 intensity 强度 ADC 模数转换器 luminance 亮度 DAC 数模转换器 chrominance 色度 PCM 脉冲编码调制
核心句子 If a sound wave is not a pure sine wave, but a linear superposition of sine waves where the highest frequency component present is f, then it is sufficient to make samples at a frequency 2f. 如果声波不是纯正弦波，而是最高频率为f的多个正弦波的线性叠加，那么按照2f的频率进行采样就足够了。
核心句子 Rather than increase the frame rate, which would require using more scarce bandwidth, a different approach is taken. Instead of displaying the scan lines in order from top to bottom, first all the odd scan lines are displayed, then the even ones are displayed. 我们没有采用提高帧率的方法，因为其需要更多宝贵的带宽，我们采用了另外一种方法。扫描线不是自顶至底依次显示，而是先显示奇数扫描线再显示偶数扫描线。
Outline Lesson 1 Signals: Audio, Image and Video Lesson 2 Systems: Linear versus Nonlinear Lesson 3 Modern Electronic Communication System Lesson 4 Audio Encoding & Video Encoding Lesson 5 Image and Video Compression Lesson 7 Channel Coding: Error Detection & Correction Lesson 8 Analog Modulation and Digital Modulation Lesson 12 Analog-to-Digital Converters (ADC)
interframe compression 核心词汇 英文 中文 algorithm complexity matrix buffer element interframe compression average motion compensation coefficient round-off error redundancy run-length encoding multicast DCT threshold HDTV videoconference
核心词汇 英文 中文 算法 复杂度 矩阵 缓存 元素 帧间压缩 平均值 运动补偿 系数 舍入误差 冗余 行程编码 多播 离散余弦变换 阈值 高清电视 视频会议
interframe compression 核心词汇 英文 中文 algorithm 算法 complexity 复杂度 matrix 矩阵 buffer 缓存 element 元素 interframe compression 帧间压缩 average 平均值 motion compensation 运动补偿 coefficient 系数 round-off error 舍入误差 redundancy 冗余 run-length encoding 行程编码 multicast 多播 DCT 离散余弦变换 threshold 阈值 HDTV 高清电视 videoconference 视频会议
核心句子 What is needed is some way to compensate for this motion. 所需要的是一种方法来补偿这种(摄像机的)运动。
核心句子 The MPEG standards do not specify how to search, how far to search, or how good a match has to be in order to count. This is up to each implementation. MPEG标准中并没有规定如何搜索，要搜索多大范围多远，也没有规定怎么评价匹配的优劣。这取决于算法实现。
Outline Lesson 1 Signals: Audio, Image and Video Lesson 2 Systems: Linear versus Nonlinear Lesson 3 Modern Electronic Communication System Lesson 4 Audio Encoding & Video Encoding Lesson 5 Image and Video Compression Lesson 7 Channel Coding: Error Detection & Correction Lesson 8 Analog Modulation and Digital Modulation Lesson 12 Analog-to-Digital Converters (ADC)
核心词汇 英文 中文 channel coding flip-flop error detection serial error correction carry parity bit shift register CRC exclusive OR Hamming Code most significant bit checksum least significant bit character BER register
核心词汇 英文 中文 信道编码 触发器 错误检测 串联的 错误纠正 进位 奇偶校验位 移位寄存器 循环冗余校验 异或运算 汉明码 最高有效位 检验和 最低有效位 字符 误码率 寄存器
核心词汇 英文 中文 channel coding 信道编码 flip-flop 触发器 error detection 错误检测 serial 串联的 error correction 错误纠正 carry 进位 parity bit 奇偶校验位 shift register 移位寄存器 CRC 循环冗余校验 exclusive OR 异或运算 Hamming Code 汉明码 most significant bit 最高有效位 checksum 检验和 least significant bit 最低有效位 character 字符 BER 误码率 register 寄存器
核心句子 Be that as it may, Hamming bits are inserted into the data stream randomly. 尽管如此，汉明位还是随机插入到数据流中。
核心句子 The only crucial point in the selection of their locations is that both the sender and receiver are aware of where they actually are. 在选择他们的位置时，唯一重要的一点就是，发送方和接收发均知道他们的位置。
Outline Lesson 1 Signals: Audio, Image and Video Lesson 2 Systems: Linear versus Nonlinear Lesson 3 Modern Electronic Communication System Lesson 4 Audio Encoding & Video Encoding Lesson 5 Image and Video Compression Lesson 7 Channel Coding: Error Detection & Correction Lesson 8 Analog Modulation and Digital Modulation Lesson 12 Analog-to-Digital Converters (ADC)
signal-to-noise ratio (SNR) 核心词汇 英文 中文 Analog Modulation transmitter AM receiver FM carrier PM modem Digital Modulation repeater FSK signal-to-noise ratio (SNR) PSK sampling rate QAM PAM
核心词汇 英文 中文 模拟调制 发射机 调幅 接收机 调频 载波 调相 调制解调器 数字调制 中继器 频移键控 信噪比 相移键控 采样率 正交幅度调制 脉冲幅度调制
signal-to-noise ratio (SNR) 核心词汇 英文 中文 Analog Modulation 模拟调制 transmitter 发射机 AM 调幅 receiver 接收机 FM 调频 carrier 载波 PM 调相 modem 调制解调器 Digital Modulation 数字调制 repeater 中继器 FSK 频移键控 signal-to-noise ratio (SNR) 信噪比 PSK 相移键控 sampling rate 采样率 QAM 正交幅度调制 PAM 脉冲幅度调制
核心句子 This makes FM modulation more immune to noise than AM and improves the overall signal-to-noise ratio of the communication system. 这使得调频比调幅更不易受噪声影响，因此也能提高通信系统的整体信噪比。
核心句子 One way to increase the binary data rate while not increasing the bandwidth requirement for signal transmission is to encode more than one bit per phase change. 在不增加带宽需求的基础上，提高二进制数据速率的方法之一是每个相位代表多个比特。
Outline Lesson 1 Signals: Audio, Image and Video Lesson 2 Systems: Linear versus Nonlinear Lesson 3 Modern Electronic Communication System Lesson 4 Audio Encoding & Video Encoding Lesson 5 Image and Video Compression Lesson 7 Channel Coding: Error Detection & Correction Lesson 8 Analog Modulation and Digital Modulation Lesson 12 Analog-to-Digital Converters (ADC)
核心词汇 英文 中文 comparator over sampling resolution processing gain accuracy noise shaping reference voltage data sheet power consumption FFT
核心词汇 英文 中文 比较器 过采样 分辨率 处理增益 精度 噪声整形 参考电压 数据手册 功耗 快速傅里叶变换
核心词汇 英文 中文 comparator 比较器 over sampling 过采样 resolution 分辨率 processing gain 处理增益 accuracy 精度 noise shaping 噪声整形 reference voltage 参考电压 data sheet 数据手册 power consumption 功耗 FFT 快速傅里叶变换
核心句子 Analog-to-digital converters (ADC) come in almost as many flavors as ice creams, and at least as much care is needed in choosing the former as is required with the latter. ADC类型像冰淇淋口味一样多，挑选时至少要像挑选冰淇淋一样细心。
核心句子 The flash converter operates by simultaneously presenting the input signal to a bank of 2^N-1 comparators, whose reference voltages are set by a resistor chain to exactly correspond to all of the possible sample levels which can be represented by the converter. 闪式ADC将输入信号同时传给2^N-1个比较器。这些比较器的参考电压由一列电阻设定，以使其值正好对应于转换器所能代表的全部采样值。
Outline Lesson 13 Phase-Locked Loops Lesson 15 How to Draw Schematic Diagrams Lesson 16 Wireless Transmission Lesson 17 The Mobile Telephone System Lesson 19 Guided Transmission Media Lesson 20 The Fiber Optic Communication System Lesson 22 The Internet Lesson 23 Third-Generation Mobile Phone Networks
Outline Lesson 13 Phase-Locked Loops Lesson 15 How to Draw Schematic Diagrams Lesson 16 Wireless Transmission Lesson 17 The Mobile Telephone System Lesson 19 Guided Transmission Media Lesson 20 The Fiber Optic Communication System Lesson 22 The Internet Lesson 23 Third-Generation Mobile Phone Networks
核心词汇 英文 中文 Phase-Locked Loop (PLL) Integrated Circuit (IC) Voltage-Controlled Oscillator (VCO) full-wave-rectified signal phase detector feedback resistor frequency synthesizer DC amplifier
核心词汇 英文 中文 锁相环 集成电路 压控振荡器 全波整流信号 鉴相器 反馈电阻 频率合成器 直流 放大器
核心词汇 英文 中文 Phase-Locked Loop (PLL) 锁相环 Integrated Circuit (IC) 集成电路 Voltage-Controlled Oscillator (VCO) 压控振荡器 full-wave-rectified signal 全波整流信号 phase detector 鉴相器 feedback resistor 反馈电阻 frequency synthesizer 频率合成器 DC 直流 amplifier 放大器
核心句子 The phase detector is a device that compares two input frequencies, generating an output that is a measure of their phase difference (if, for example, they differ in frequency, it gives a periodic output at the difference frequency). 鉴相器是这样一个设备：他比较两个输入信号的频率，然后产生一个体现两个输入信号的相位差的信号。（比如，如果两个信号有频差的话，鉴相器的输出信号是一个以此频差为频率的周期信号。）
核心句子 In frequency modulation, information is encoded onto a “carrier” signal by varying its frequency proportional to the information waveform. 在频率调制中，载波信号频率随着信息波形而变化，从而将信息编码到载波上。
Outline Lesson 13 Phase-Locked Loops Lesson 15 How to Draw Schematic Diagrams Lesson 16 Wireless Transmission Lesson 17 The Mobile Telephone System Lesson 19 Guided Transmission Media Lesson 20 The Fiber Optic Communication System Lesson 22 The Internet Lesson 23 Third-Generation Mobile Phone Networks
核心词汇 英文 中文 schematic counter troubleshooting shift register pin supply voltage
核心词汇 英文 中文 电路原理图 计数器 故障排除 移位寄存器 引脚 电源电压
核心词汇 英文 中文 schematic 电路原理图 counter 计数器 troubleshooting 故障排除 shift register 移位寄存器 pin 引脚 supply voltage 电源电压
Outline Lesson 13 Phase-Locked Loops Lesson 15 How to Draw Schematic Diagrams Lesson 16 Wireless Transmission Lesson 17 The Mobile Telephone System Lesson 19 Guided Transmission Media Lesson 20 The Fiber Optic Communication System Lesson 22 The Internet Lesson 23 Third-Generation Mobile Phone Networks
核心词汇 英文 中文 wireless transmission/communication visible light electromagnetic spectrum X-ray wavelength LF radio MF microwave HF infrared laser ultraviolet (UV) multipath fading
核心词汇 英文 中文 无线传输/通信 可见光 电磁波谱 X射线 波长 低频 无线电波 中频 微波 高频 红外线 激光 紫外线 多径衰落
核心词汇 英文 中文 wireless transmission/communication 无线传输/通信 visible light 可见光 electromagnetic spectrum 电磁波谱 X-ray X射线 wavelength 波长 LF 低频 radio 无线电波 MF 中频 microwave 微波 HF 高频 infrared 红外线 laser 激光 ultraviolet (UV) 紫外线 multipath fading 多径衰落
核心句子 As a rule of thumb, when 𝜆 is in meters and 𝑓 is in MHz, 𝜆𝑓≈300. 根据经验，当波长𝜆 以米为单位，频率𝑓以兆赫兹为单位时，我们有𝜆𝑓≈300。
核心句子 AM radio broadcasting uses the MF band, which is why the ground waves from Boston AM radio stations cannot be heard easily in New York. 调幅无线电广播使用中频频段，因此来自波士顿调幅无线电台的地波很难在纽约收听到。
Outline Lesson 13 Phase-Locked Loops Lesson 15 How to Draw Schematic Diagrams Lesson 16 Wireless Transmission Lesson 17 The Mobile Telephone System Lesson 19 Guided Transmission Media Lesson 20 The Fiber Optic Communication System Lesson 22 The Internet Lesson 23 Third-Generation Mobile Phone Networks
packet-switching network 核心词汇 英文 中文 overload FDD microcell GSM handoff/handover CDMA base station (BS) SIM packet-switching network time slot channel assignment directional antenna
核心词汇 英文 中文 过载 频分双工 微蜂窝 全球移动通信系统 （越区）切换 码分多址 基站 用户身份模块 分组交换网 时隙 信道分配 定向天线
packet-switching network 核心词汇 英文 中文 overload 过载 FDD 频分双工 microcell 微蜂窝 GSM 全球移动通信系统 handoff/handover （越区）切换 CDMA 码分多址 base station (BS) 基站 SIM 用户身份模块 packet-switching network 分组交换网 time slot 时隙 channel assignment 信道分配 directional antenna 定向天线
核心句子 The key idea that gives cellular systems far more capacity is the use of relatively small cells and the reuse of transmission frequencies in nearby (but not adjacent) cells. 使蜂窝系统具有很大容量的关键在于使用了相对较小的蜂窝小区和在附近（但不是临近的）小区间应用频谱复用。
核心句子 In an area where the number of users has grown to the point that the system is overloaded, the power can be reduced and the overloaded cells split into smaller microcells to permit more frequency reuse, as shown in Figure 17.1(b). 在一个地区，如果用户数量太大以致系统过载，我们就可以通过减少传输功率并将过载小区分为更小的微蜂窝小区来实现更高的频率复用（见图17.1(b)）。
Outline Lesson 13 Phase-Locked Loops Lesson 15 How to Draw Schematic Diagrams Lesson 16 Wireless Transmission Lesson 17 The Mobile Telephone System Lesson 19 Guided Transmission Media Lesson 20 The Fiber Optic Communication System Lesson 22 The Internet Lesson 23 Third-Generation Mobile Phone Networks
核心词汇 英文 中文 guided medium refraction twisted pair reflection coaxial cable transmission medium fiber optic LED delay conductor
核心词汇 英文 中文 导向介质 折射 双绞线 反射 同轴电缆 传输介质 光纤 发光二极管 时延 导体
核心词汇 英文 中文 guided medium 导向介质 refraction 折射 twisted pair 双绞线 reflection 反射 coaxial cable 同轴电缆 transmission medium 传输介质 fiber optic 光纤 LED 发光二极管 delay 时延 conductor 导体
核心句子 Coaxial cables used to be widely used within the telephone system for long-distance lines but have now largely been replaced by fiber optics on long-haul routes. 同轴电缆曾经广泛用于长途线路电话系统中。不过，如今大部分都被光纤替代了。
核心句子 One thousand twisted pairs 1 km long weight 8000 kg. Two fibers have more capacity and weight only 100 kg, which greatly reduces the need for expensive mechanical support systems that must be maintained. 一公里长的1000对双绞线重达8000kg。然而，两根光纤就能拥有更多的容量，且重量只有100kg。这就大大减少了对必须维护的昂贵机械支持系统的需求。
Outline Lesson 13 Phase-Locked Loops Lesson 15 How to Draw Schematic Diagrams Lesson 16 Wireless Transmission Lesson 17 The Mobile Telephone System Lesson 19 Guided Transmission Media Lesson 20 The Fiber Optic Communication System Lesson 22 The Internet Lesson 23 Third-Generation Mobile Phone Networks
satellite communication 核心词汇 英文 中文 carrier source transmission loss channel coupler decision circuit photodetector BER satellite communication semiconductor
核心词汇 英文 中文 载波信号源 传输损耗 信道耦合器 判决电路 光电检测器 误码率 卫星通信 半导体
satellite communication 核心词汇 英文 中文 carrier source 载波信号源 transmission loss 传输损耗 channel coupler 信道耦合器 decision circuit 判决电路 photodetector 光电检测器 BER 误码率 satellite communication 卫星通信 semiconductor 半导体
核心句子 A brief discussion of each block in this figure will give us a good feel for the main elements of a communication system. 对图中各模块的简要讨论有助于理解通信系统的主要元素。
核心句子 Examples include fibers used in the ground portion of a satellite communications system and fibers used in relaying cable television signals. 典型例子包括用于卫星通信系统中地面部分的光纤链路和用于有线电视信号中继的光纤链路。
Outline Lesson 13 Phase-Locked Loops Lesson 15 How to Draw Schematic Diagrams Lesson 16 Wireless Transmission Lesson 17 The Mobile Telephone System Lesson 19 Guided Transmission Media Lesson 20 The Fiber Optic Communication System Lesson 22 The Internet Lesson 23 Third-Generation Mobile Phone Networks
核心词汇 英文 中文 Internet packet ISP router modem protocol FTTH firewall backbone intranet host virtual machine data center DSL
核心词汇 英文 中文 互联网，因特网 数据包 互联网服务提供商 路由器 调制解调器 协议 光纤到户 防火墙 主干网，骨干网 内联网 主机 虚拟机 数据中心 数字用户线
核心词汇 英文 中文 Internet 互联网，因特网 packet 数据包 ISP 互联网服务提供商 router 路由器 modem 调制解调器 protocol 协议 FTTH 光纤到户 firewall 防火墙 backbone 主干网，骨干网 intranet 内联网 host 主机 virtual machine 虚拟机 data center 数据中心 DSL 数字用户线
核心句子 To joint the Internet, the computer is connected to an Internet Service Provider, or simply ISP, from who the user purchases Internet access or connectivity. 为了加入互联网，计算机要连接到一个互联网提供商（简称ISP）。互联网用户从ISP购买互联网接入/连接服务。
核心句子 Despite these difficulties, it makes sense to regard such machines as being on the Internet while they are connected to their ISPs. 尽管有这些困难，当这些机器连接到其ISP上时，将他们视为“在互联网上”是完全合理的。
Outline Lesson 13 Phase-Locked Loops Lesson 15 How to Draw Schematic Diagrams Lesson 16 Wireless Transmission Lesson 17 The Mobile Telephone System Lesson 19 Guided Transmission Media Lesson 20 The Fiber Optic Communication System Lesson 22 The Internet Lesson 23 Third-Generation Mobile Phone Networks
quality of service (QoS) 核心词汇 英文 中文 frequency reuse authentication UMTS authorization air interface quality of service (QoS) hard handover data rate soft handover LTE
核心词汇 英文 中文 频率复用 认证 通用移动通信系统 授权 空中接口 服务质量 硬切换 数据率 软切换 长期演进
quality of service (QoS) 核心词汇 英文 中文 frequency reuse 频率复用 authentication 认证 UMTS 通用移动通信系统 authorization 授权 air interface 空中接口 quality of service (QoS) 服务质量 hard handover 硬切换 data rate 数据率 soft handover 软切换 LTE 长期演进
核心句子 The term (air interface) is a fancy name for the radio communication protocol that is used over the air between the mobile device and cellular base station. 空中接口这个词是对用于移动用户和蜂窝小区之间的无线通信协议的一个炫酷称呼。
核心句子 This way of doing a handover is called a soft handover to distinguish it from a hard handover, in which the mobile disconnects from the old base station before connecting to the new one. 这种切换方式叫做软切换，以区分于硬切换。在硬切换中，移动端在连接到一个新的基站前必须和旧基站断开。
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