Weitere Kapitel dieses Buchs durch Wischen aufrufen
In a wide variety of communication systems, modulation as a fundamental technique plays a very important role in data transmission through air within a specified spectral bandwidth. A modulation signal, which is usually represented by a low-frequency baseband signal and is commonly referred to as an information-bearing signal, varies or modulates one of three parameters: amplitude, phase, and frequency of the radiofrequency (RF) carrier signal such that the baseband signal is carried by a varied parameter of the carrier signal through atmosphere propagation to the destination. Why does the information-bearing signal need to modulate a high-frequency carrier signal for this transmission? This is necessary because the size of the antenna used to radiate the signal to free space depends on the wavelength λ of the transmitted signal. The wavelength λ is equal to c/f, where c is the speed of light and equals 3 × 108 m/s, and f is the frequency of the transmitted signal. For cellular communication systems, antennas are typically λ/4 in size . If a baseband signal with a frequency of 15 kHz were to be transmitted through an antenna without modulating a carrier signal, the size of the antenna would be λ/4 = 5,000 m. However, it is only 8 cm if a carrier signal with a frequency of 900 MHz is modulated by such a baseband signal. For this reason, a high-frequency signal usually called a carrier signal is needed for all wireless communication systems to carry the modulation baseband signal. Thus, modulation is a necessary process in all wireless communication systems. Through this book, we mainly consider either the phase modulation scheme or a combination of an amplitude and phase modulation scheme such as M-QAM for its simple implementation and robust performance. In the phase modulation scheme, the information-bearing baseband signal is used to change the phase of a sinusoidal carrier signal whenever the polarity of the baseband signals changes. The phase change of the carrier signal, indicating either 1 or 0, is carried by the carrier signal.
Bitte loggen Sie sich ein, um Zugang zu diesem Inhalt zu erhalten
Sie möchten Zugang zu diesem Inhalt erhalten? Dann informieren Sie sich jetzt über unsere Produkte:
Sklar, B. (2002). Digital communications: Fundamentals and applications (p. 168). India: Pearson Education Asia.
Wang, A. Y., & Sodini, C. G. (2006). On the energy efficiency of wireless transceivers. In ICC 2006 Proceedings (pp. 3783–3788).
McCune, E. (2015). A technical foundation for RF CMOS power amplifiers. IEEE Solid-State Circuits Magazine, 8(2), 75–82. CrossRef
Joung, J., Ho, C. K., Adachi, K., & Sun, S. (2015). A survey on power amplifier centric techniques for spectrum- and energy-efficient wireless communication. IEEE Communication Surveys and Tutorials, 17(1), 315–333. CrossRef
Cripps, S. C. (1999). RF power amplifiers for wireless communications (p. 49). Norwood, MA: Artech House.
Wimpenny, G. (2012, February 6). Envelope tracking power amplifier characterization (White Paper). Nujira limited. Retrieved from www.nujira.com
Application Report, “GC5325 Envelope Tracking,” Texas Instruments, SLWA058B, April 2010.
Cripps, S. C. (2002). Advanced techniques in RF power amplifier design (pp. 4–5). Norwood, MA: Artech House.
Buzzi, S., Chih-Lin, I., Klein, T. E., Vincent Poor, H., Yang, C., & Zappone, A. (2016). A survey of energy-efficient techniques for 5G networks and challenges ahead. IEEE Journal on Selected Areas in Communications, 34(4), 697–709. CrossRef
Ziemer, R. E., & Tranter, W. H. (2002). Principles of communications: Systems modulation and noise (5th ed.). New York: Wiley.
Feher, K. (1995). Wireless and digital communications: Modulation & spread spectrum applications. Upper Saddle River, NJ: Prentice-Hall PTR.
ZigBee Alliance. (2006, December). ZigBee Specifications (Version 1.0). Retrieved from http://www.zigbee.org/
Austin, M. C., & Chang, M. U. (1981). Quadrature overlapped raised-cosine modulation. IEEE Transactions on Communications, COM-29(3), 237–249. CrossRef
Le-Ngoc, T., & Feher, K. (1983). Performance of IJF-OQPSK modulation schemes in a complex interference environment. IEEE Transactions on Communications, COM-31(1), 137–144. CrossRef
Seo, J. S., & Feker, K. (1985). SQAM: a new superposed QAM modem technique. IEEE Transactions on Communications, COM-33(3), 296–300. CrossRef
Gao, W., Ju, D., & Wu, Y. Self-convolving minimum shift keying (SCMSK) modem for satellite system. In Proceedings of IEEE Singapore ICCS’88 (pp. 341–345).
Gao, W., & Feher, K. (1996). All digital reverse modulation architecture based carrier recovery implementation for GMSK and compatible FQPSK. IEEE Transactions on Broadcasting, 42(1), 55–62. CrossRef
Proakis, J. G. (1995). Digital communications (3rd ed.). New York: McGraw-Hill. MATH
Simon, M. K. (2001, June). Bandwidth-efficient digital modulation with application to deep-space communications. Deep-space communications and navigation series.
Nyquist, H. (1928). Certain topic in telegraph transmission. Transactions of the AIEE, 47(2), 617–644.
Tenbroek, B., Strange, J., Nalbantis, D., Jones, C., Flowers, P., Brett, S., et al. (2008). Single-chip tri-band WCDMA/HSDPA transceiver without external SAW filters and with integrated TX power control. In ISSCC 2008 (pp. 202–204).
Jussila, J. (2003, June). Analog baseband circuits for WCDMA direct conversion receivers . PhD Dissertation, Helsinki University of Technology, Finland.
Li, Z., Li, M., Zhao, D., Ma, D., Ni, W., & Ouyang, Z. (2010). TD-SCDMA/HSDPA transceiver and analog baseband chipset in 0.18-μm CMOS process. IEEE Transactions on Circuits and Systems-II, 57(2), 90–94. CrossRef
Oppenheim, A. V., Schafer, R. W., & Buck, J. R. (1999). Discrete-time signal processing. Upper Saddle River, NJ: Prentice Hall.
Yang, K. (2006, April 13). Flatten DAC frequency response. END Magazine, 65–74.
Multiband OFDM physical layer proposal for IEEE 802.15 Task Group 3a (2004, September 14). MBOA-SIG multiband OFDM alliance SIG.
- Bandwidth-Efficient Modulation with Frequency Division Multiple Access (FDMA)
- Chapter 2
Neuer Inhalt/© Filograph | Getty Images | iStock