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Low-Power Baseband Processors for Communications
Published in Christian Piguet, Low-Power Processors and Systems on Chips, 2018
Baseband signals are all signals in a radio system, which are not modulated onto the carrier wave. In a cellular phone, this means all signals except those in the radio frequency (RF) part of the phone. This chapter discusses processors for digital baseband signal processing, known as digital baseband DSP processors (DBBP). Figure 6.1 defines the basic partitioning of a radio communication system from both functional and hardware points of view. A DBBP plays an important role in both the transmitter and the receiver. In a transmitter, the DBBP converts the data from application sources to a format adapted to the radio channel. In a receiver, a DBBP recovers symbols from the distorted analog baseband signal and translates them to a bit stream with acceptable bit error rate (BER) for applications. Figure 6.1.bdescribes functions in a DBBP. The most power-consuming parts are in the receiver, with functions such as synchronization, demodulation, and forward error correction. This chapter introduces the implementation of low-power DBBP. Detailed theory and knowledge of DSP for digital communications may be found elsewhere [2].
Introduction to Localarea Networks
Published in Paul J. Fortier, Handbook of Local Area Network Software, 1991
Typical of most local area networks in use today is the use of serial data transmission media and techniques. This is due to the LANs’ use in high-speed transmission, over moderately long distances, and the desire to keep wiring costs at reasonable levels. Due to this use, sophisticated line drivers and receivers (next section) have to be used, with only one driver/receiver interface unit per device. Transmission of the sequence of bits is typically strictly done digitally, using baseband or broadband signaling techniques. Baseband signaling is a technique in which the digital signal is transmitted in its original form with no changes induced by modulation techniques. Broadband signaling is a technique that provides a means to break up the transmission media into multiple channels over the same conduit by frequency division of the bandwidth [Fortier 1988]. Either of these techniques can be hosted on coaxial cable. Coaxial cable is a wire media made up of a central copper wire core encased in an insulator that is covered with a woven copper outer mesh.
Fundamentals of wireless networks
Published in Matthew N. O. Sadiku, Optical and Wireless Communications, 2018
Information is often represented in some form of electrical pulses that are not suitable for transmission over the air. In other words, baseband signaling is not sufficient for sending signals over any distance. The signal must be modulated onto an RF carrier. Modulation is the means of adding the message information to the radio carrier. Earlier wireless systems used analog modulation techniques, but present and next generation wireless networks use digital modulation schemes. Two of the various digital modulation techniques widely used for wireless systems are π/4 phase-shifted quadrature phase shift keying (π/4-QPSK) in North America and Japan and Gaussian minimum shift keying (GMSK) in the European GSM system.
Performance of blind detection frame work using energy detection approach for local sensing in intelligent networks
Published in International Journal of Computers and Applications, 2021
K. Venkata Vara Prasad, P. Trinatha Rao
To sense channel N with this sensing technique, the sensing receiver is tuned to that channel and the RF signal is converted to an Intermediate Frequency (IF) where a 7 MHz wide filter is used to filter out signals outside the channel N. After IF filtering, the signal is down-converted to a base-band signal. The base-band signal is band-limited to ±3 MHz. The band-limited signal is complex (in-phase and quadrature) sampled at 7 MHz. The sampled signal is where is the signal component and is the noise component. The power of is and the power of is .