New answers tagged

0

Under the white Gaussian noise assumption, the optimal decoder would be to minimize each window of $7$ bits, that is take you first 7 symbols $$s_1 = [\:\:1,−1,\:\:1,\:\:1,\:\:1,−1,\:\:1]$$ and compute two metrics $$c_0 = \Vert s_1 - b_0 \Vert_2^2 = 2^2 + 2^2 + 2^2 + 2^2 + 2^2 = 20$$ $$c_1 = \Vert s_1 - b_1 \Vert_2^2 = 2^2 + 2^2 = 4$$ where $b_1 = [−1,−1,−...


1

I want to ask the definition of MIMO(Multi-input Multi-output ) If there are one transmitter and one receiver,each of them has N antennas,N>1. So i can say it is a MIMO system. Any communication system comprising of a transmitter with $N >1$ and receiver comprising of $M>1$ antennas is considered to be a MIMO system. So, this is not only limited to $N=...


0

Convolutional codes spread protection across a relatively large number of bits - when the decoder makes a mistake it impacts bits over that larger range. Convolutional decoding is not infallible, especially at low Eb/No (i.e. low SNR), their performance is thus worse than uncoded data for low ranges (where mistakes are limited only to the immediate bits ...


2

Well, you're not going to send and receive those symbols directly, you know? What you'll need to convey the information over a channel is a waveform. Your receiver will then typically use the same waveform to correlate the signal. Say you are using root raised cosine pulses to transmit, then your receiver will employ a root raised cosine filter as a pulse ...


3

QAM is a digital modulation scheme. As such it is one way of implementing a physical layer that allows to convey digital information over a given medium. QAM is frequently used in all kinds of systems, including wireless (cf. broadcast TV and yes, also WiFi) as well as wired (Ethernet uses some variations of QAM as well). What kind of information you convey ...


3

The receiver/transmitter pair in B's possession is operating in half-duplex mode. As you say "$A$ give $x$ to $B$, then $B$ give $x$ to $C$" which specifies that while $B$ ls listening to what $A$ is telling it (the $x$ that is being given to $B$), the transmitter in $B$'s possession must remain silent until $B$ has completely received $x$. It is only ...


1

CDMA is not a protocol. It's a multi-access scheme. A BER can't be generally given for a multi-access scheme. You'll need to define your access characteristics, SNR scenario, look at the specific multi-user detector for your specific modulation. Hence, BlackMath is right: you'll need to go down the long route: Learn about CDMA's basics; do a lot of ...


1

Point-to-point means direct (there is no intermediate node) communication between a transmitter and receiver. The transmitter and/or receiver can be equipped with multiple-antennas, and use either STBC or spatial multiplexing. In your presented scenario, the channel is called interference channel, if the message of $t_i$ is intended only to $r_i$, but $r_j$...


1

Point to point typically refers to single devices transmitting to each other, regardless of how many antennas they have. The important thing is that in point to point systems, there is no interference from other transmissions, you only have signal and noise. If transmitter and receiver have multiple antennas, you would typically call it MIMO, to specify ...


0

Well, it seems the authors assume a setup where there are separate data receivers (DR) and energy receivers (ER) ("To achieve a balanced user experience for separately located datareceivers (DRs) and energy receivers (ERs) in the network, joint transmit beamforming vectors are optimized [...]"). In that setup, $s_k^E$ would be symbols that are used for ...


1

Yes, you can bandpass the QPSK signal before matched filtering and demodulation if you wish to do so, but what you need to devote some thought to is whether such an action is a wise decision. The answer might depend on various parameters that you have left unspecified. Bandwidth of bandpass filter $<$ QPSK signal bandwidthIn this case, the filtered QPSK ...


Top 50 recent answers are included