add module-overview

morea/overview/assessment-CHANGE-ME.md

@@ -0,0 +1,14 @@
+---
+title: "CHANGE ME"
+published: false
+morea_id: assessment-CHANGE-ME
+morea_summary: "CHANGE ME"
+morea_outcomes_assessed:
+ # - outcome-CHANGE-ME
+morea_type: assessment
+morea_start_date: "2021-07-16T09:00"
+morea_labels:
+---
+# CHANGE ME
+
+TBD

morea/overview/experience-CHANGE-ME.md

@@ -0,0 +1,17 @@
+---
+title: "CHANGE ME"
+published: false
+morea_id: experience-CHANGE-ME
+morea_type: experience
+morea_summary: "CHANGE ME"
+morea_start_date: "2021-07-15T23:00"
+morea_labels:
+---
+
+# CHANGE ME
+
+TBD
+
+## Submission Instructions
+
+TBD

morea/overview/module-overview.md

@@ -0,0 +1,24 @@
+---
+title: "Overview -- Wireless vs Wired Communications"
+published: true
+morea_coming_soon: false
+morea_id: module-overview
+morea_prerequisites:
+morea_outcomes:
+  - outcome-overview
+morea_readings:
+  - reading-building-blocks
+  - reading-fading-interference
+morea_experiences:
+  # - experience-CHANGE-ME
+morea_assessments:
+  # - assessment-CHANGE-ME
+morea_type: module
+morea_icon_url: /morea/overview/02-Wireless-vs-Wired.jpeg
+morea_start_date: "2024-01-08"
+morea_end_date: "2024-01-09"
+morea_labels:
+morea_sort_order: 21
+---
+
+Overview of the key differences between wireless and wired communication systems

morea/overview/outcome-overview.md

@@ -0,0 +1,11 @@
+---
+title: "Key features of wireless channels and wireless communication systems"
+published: true
+morea_id: outcome-overview
+morea_type: outcome
+morea_sort_order: 10
+---
+
+  * You understand the two key differences between wireless channels and wired channels.
+  * You understand the basic building blocks of a wireless communication system.
+  * You understand the role of each block in combatting the challenges in wireless communications.

morea/overview/reading-building-blocks.md

@@ -0,0 +1,66 @@
+---
+title: "Building Blocks of Communication Systems"
+published: true
+morea_id: reading-building-blocks
+morea_summary: "Building blocks of a typical communication system"
+# morea_url: https://github.com/airbnb/javascript
+morea_type: reading
+morea_labels:
+---
+
+## Basic building blocks
+
+Here is the block diagram of a typical <span style="color: red;">point-to-point</span> communication system.
+
+<figure>
+  <img src="02-building-blocks.png" alt="Building blocks of a typical communication system" width="500">
+  <figcaption>Building blocks of a typical communication system. The top row are blocks in the transmitter, and the bottom row are in the receiver.</figcaption>
+</figure>
+
+Note that for each block in the transmitter, there is a counterpart in the receiver. Let us divide into each block and discuss their roles.
+
+## Source Encoder and Source Decoder
+
+<figure>
+  <img src="02-building-blocks-source-coding.png" alt="Source coding in a typical communication system" width="500">
+  <figcaption>The source encoder converts the source signal into a binary sequence, and the source decoder reconstructs the source signal.</figcaption>
+</figure>
+
+The source encoder "encodes" the message that the transmitter wishes to send. Here, "encodes" includes, but is not limited to, sampling the continuous-time signal to get a discrete-time signal, quantization, and compression.
+
+For example, if we make a phone call, the source is an analog audio signal. Then the source encoder at the transmitter will sample, quantize, and compress the source and output a binary sequence. The source decoder at the receiver will reconstruct the analog audio signal.
+
+Even if the source is already a binary sequence (e.g., a text message that is natively represented by a sequence of bits in our phone), the source encoder is still useful in compressing the original binary sequence into a shorter binary sequence.
+
+Source coding is an important topic in information theory. But we will not dive deep into this topic in this course.
+
+## Channel Encoder and Channel Decoder
+
+<figure>
+  <img src="02-building-blocks-channel-coding.png" alt="Channel coding in a typical communication system" width="500">
+  <figcaption>The channel encoder adds redundancy to combat the channel errors, and the channel decoder "decodes" the message.</figcaption>
+</figure>
+
+The channel encoder *adds redundancy* to the binary sequence produced by the source encoding. This might seem counterintuitive -- didn't the source encoder just compress the source signal to *reduce* redundancy?
+
+Well, the source encoder removes the inherent redundancy in the source signal, while the channel encoder adds *a different type of redundancy* to combat the imperfections of the channel. 
+
+We will discuss some simple channel coding and decoding schemes in this course.
+
+## Modulator and Demodulator
+
+<figure>
+  <img src="02-building-blocks-modulation.png" alt="Modulation in a typical communication system" width="500">
+  <figcaption>The modulator "places" the signal in the correct space, time, and frequency, and the demodulator retrieves the signal.</figcaption>
+</figure>
+
+The radio spectrum is a very scarce resource. [Mobile operators spend tens of billions of dollars to buy a few hundred MHz of spectrum](https://www.spglobal.com/marketintelligence/en/news-insights/latest-news-headlines/big-4-wireless-carriers-spent-100b-on-5g-spectrum-was-it-worth-it-68488095).
+> Verizon, meanwhile, spent $45.45 billion in the C-band spectrum auction in 2021 when the Federal Communications Commission auctioned 280 MHz of spectrum in the 3.7 GHz-3.98 GHz band. AT&T dished out $23.41 billion in the C-band auction and then followed that up by shelling out an additional $9.08 billion in the subsequent 3.45 GHz auction, which ended earlier this month. All told, the carrier spent $32.49 billion on mid-band spectrum across the two auctions. 
+>
+> _- S&P Global_
+
+Therefore, the transmitter needs to carefully "modulate" the signal into the correct frequency band, and the receiver needs to "demodulate" (i.e., retrieve) the signal from the correct band.
+
+Modulation is also important in avoiding *multi-user interference*. For example, in LTE, if two AT&T cell phones are making phone calls in the same room, their signals will be modulated into different frequency bins withint the AT&T spectrum.
+
+Of course, the frequency is not the only degree of freedom. Modulation can place signals in different space and time. We will elaborate on this important topic later.

morea/overview/reading-fading-interference.md

@@ -0,0 +1,37 @@
+---
+title: "Fading and Interference in Wireless Communications"
+published: true
+morea_id: reading-fading-interference
+morea_summary: "Wireless communication systems need to combat fading and interference"
+# morea_url: https://github.com/airbnb/javascript
+morea_type: reading
+morea_labels:
+---
+
+## Key Challenges in Wireless Communications
+
+There are two key challenges in wireless communications:
+- *Fading*: The wireless channel is very random. A change of weather or a sudden change in the environment (e.g., people moving around) will change the channel condition. This changes happen in milliseconds or less.
+- *Interference*: The signals propagate in the open space, instead of through a conduit such as a cable. Therefore, the receiver gets signals intended for someone else, which are interference to its own communication.
+
+Both challenges are *unique* in wireless communications.
+
+## How to Deal With Fading?
+
+<figure>
+  <img src="02-building-blocks-channel-coding.png" alt="Channel coding in a typical communication system" width="500">
+  <figcaption>The channel encoder and decoder are key modules to deal with fading.</figcaption>
+</figure>
+
+As we discussed earlier, the channel encoder adds redundancy to combat the imperfections of the channel. To be specific, the imperfections of the channel refer to fading, among others (e.g., additive noises).
+
+As we will see later, compared to other channel imperfections (e.g., noises), fading is much harder to deal with. Therefore, channel coding is particularly important in wireless communication systems.
+
+## How to Deal With Interference
+
+<figure>
+  <img src="02-building-blocks-modulation.png" alt="Modulation in a typical communication system" width="500">
+  <figcaption>The modulator and demodulator are key modules to deal with multi-user interference.</figcaption>
+</figure>
+
+Modulation plays a key role in avoiding *multi-user interference*. We will explore various dimensions of the propagation environment (e.g., space, time, frequency) and discuss how to "arrange" signals from different users so that multi-user interference is minimized.