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| 姓名：(美)谢(Tse D) (美)维斯瓦纳斯(Viswanath P)著 作者简介： 作品：《无线通信基础:英文版》 |
| 插图： consider the baseband uplink signal of a user given in (4.1). due to the abrupttransitions (from + 1 to -1 and vice versa) of the pseudonoise sequences s,,,the bandwidth occupied by this signal is very large. on the other hand, thesignal has to occupy an allotted bandwidth. as an example, we see that the is-95 system uses a bandwidth of 1.2288 mhz and a steep fall off after 1.67 mhz.to fit this allotted bandwidth, the signal in (4.1) is passed through a pulseshaping filter and then modulated on to the carrier. thus though the signal in(4.1) has a perfect papr (equal to 1), the resulting transmit signal has a largerpapr. the overall signal transmitted from the base-station is the superpositionof all the user signals and this aggregate signal has papr performance similarto that of the narrowband system described in the previous section.in the narrowband system we saw that all users can maintain high sinrdue to the nature of the allocations. in fact, this was the benefit ga 更多 |
| 1 introduction 1.1 book objective 1.2 wireless systems 1.3 book outline 2 the wireless channel 2.1 physical modeling for wireless channels 2.1.1 free space, fixed transmit and receive antennas 2.1.2 free space, moving antenna 2.1.3 reflecting wall, fixed antenna 2.1.4 reflecting wall, moving antenna 2.1.5 reflection from a ground plane 2.1.6 power decay with distance and shadowing 2.1.7 moving antenna, multiple reflectors 2.2 input/output model of the wireless channel 2.2.1 the wireless channel as a linear time-varying system 2.2.2 baseband equivalent model 2.2.3 a discrete-time baseband model discussion 2.1 degrees of freedom 2.2.4 additive 更多 |
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