Antenna Handbook

Network and Connectivity

Network Topologies

The term network topology describes how devices are connected to each other within the network. It describes how many
connections each device has, in what order, and what sort of hierarchy. Typical network configurations include mesh
topology, ring topology, star topology, and tree topology. Each topology has a different level of fault tolerance. 


The topology in each node is directly connected to some or all the other nodes present in the
network. This redundancy makes the network highly faulttolerant, but the escalated costs
may limit this topology to highly critical networks.High Redundancy



All network nodes are connected sequentially to a backbone, except that the backbone ends at the starting node, forming a ring. The failure of one node will result in changing the direction of the data traffic since the topology is Bi-directional . High Redundancy. 



A root node is connected to two or more sub-level nodes, which themselves are connected hierarchically to sub-level nodes. Physically.Medium Redundancy.




Also known as hub and spoke. All the nodes in the network are connected to a central device like a hub or switch via cables. Failure of individual nodes or cables does not necessarily create downtime in the network, but the failure of a central device can. Low Redundancy.


source : https://broadbandusa.ntia.doc.gov/sites/default/files/2022-12/Introduction_to_Broadband_and_High_Speed_Internet_FINAL_0.pdf

What is Dark Fiber ?

Dark fiber refers to optical fiber infrastructure that has not yet been lit (*lit fiber), meaning it is installed but is not yet being used (no data transmission). 

Dark fiber is rented by broadband providers who need to control their own network, so instead of leasing a service, they lease infrastructure that allows them to build their own network with their own equipment. 

Dark fiber gives clients the capacity to increase bandwidth as needed without paying any additional monthly costs and decreases dependence on carrier response times during events and for upgrades. 

 Dark fiber is usually priced per strand per mile for a set period. The dark fiber providers often offer their client the option of an indefeasible right of use (IRU)** which can range between 20 to 30 years, paid upfront along with annual payments for maintenance.

*Lit Fiber: This term is the opposite of dark fiber and refers to a fiber optic cable that is active and able to transmit data. ** Indefeasible Right of Use (IRU) : A contractual agreement (temporary ownership) of a portion of the capacity of a fiber optic cable.  

Symmetric vs Asymmetric for Upload and Download Data


Symmetrical Communication 

Symmetrical communication links are just as they sound. They have the same download and upload rates. For example, a 500/500 Mbps fiber Internet link offers download and upload speeds of 500 Mbps.


Asymmetrical Communication 

Asymmetrical communication links, on the other hand, do not have the same download/upload rates. For example, 25/3 denotes a download speed of 25 Mbps and an upload speed of 3 Mbps. Asymmetrical data communication can make more efficient use of bandwidth than symmetrical data flows, since generally, most users will download more data than they upload

Middle Mile & Last Mile Networks


Interconnected networks that transmit data between and across countries and continents.

Middle Mile The electronics and circuitry that carry a signal from interconnection points and aggregation facilities to a Central Office or Point of Presence. 

Last Mile The electronics and circuitry that deliver the Internet service to a household.

*Point of Presence(POP): Demarcation point, access point, or physical location at which two or more networks or communication devices share a connection. 

**Example of Middle Mile Aggregation Facility is An Internet Exchange Point (IXP), which is a physical location through which Internet infrastructure companies such as ISPs connect with each other.

 ***Example of Middle Mile Interconnect Facility is a Data Center, which is a facility responsible for driving Internet content delivery and managing network resources.

source : https://broadbandusa.ntia.doc.gov/sites/default/files/2022-12/Introduction_to_Broadband_and_High_Speed_Internet_FINAL_0.pdf

What is Broadband Internet ?

The term Broadband was introduced in the late 1990’s and it commonly refers to high-speed Internet access that is always on and faster than the traditional dial-up access (Maximum of 56kBits/s) 1. Broadband is accessed through various high-speed transmission technologies that allow the data to move faster.

High-Speed Internet is delivered with one of two Broadband technologies. The first technology is physical wire and cables to connect the networks to the Internet, and this is called Wired broadband (e.g., Fiber Optic Cable). The other is wireless technology (e.g., Cellular 5G), and it’s called Wireless Broadband. Each connection method is capable of providing high-speed Internet, but each differs in its own way.

The Federal Communications Commission (FCC) defines basic broadband as transmission speeds of at least 25 Mbps (megabits per second) downstream (from the Internet to the user’s computer) and 3 Mbps upstream (from the user’s computer to the Internet). Infrastructure Investment and Jobs Act (IIJA) defines underserved broadband as an Internet speed of less than 100 Mbps downstream and 20 Mbps upstream.

Broadband or High Speed Internet 

Broadband in telecommunication means a wide bandwidth which can transport multiple signals over a “broad” range of frequencies and support different internet traffic types, allowing multiple data streams to be sent at once.

High-speed Internet is a generic term used for Internet service that is faster than the average. Traditionally, the way to determine if a connection is high-speed is to test its ability to connect multiple devices simultaneously to allow streaming and access to modern applications.

In essence, the terms “Broadband” and “High-Speed Internet” are mostly interchangeable when the internet speeds are at the FCC standards, or higher (i.e., a minimum of 25Mbps for download & 3Mbps for upload).

Bandwidth 

Bandwidth determines the amount of information that can be transmitted across a given path in a given unit of time. In other words, bandwidth is the size of the medium used to transmit data. The larger the size the more data you can transfer. 

Bandwidth Analogy 

The best way to explain bandwidth is to use an analogy (See the figure below). Think of your bandwidth like a highway, and your data as cars that travel the same speed. The more lanes you have on the highway, the more cars can travel at a time – it will take 5 cars longer to get to their destination on a 1-lane road than it would on a 5-lane highway.


Throughput & Latency

Throughput 
The amount of a data that a system can transmit over a medium within a specified time. Measured in Megabits* per seconds (Mbps).


Latency 
Network latency, sometimes called lag, is the term used to describe delays in communication over a network. It is a measurement of the time it takes to send data and receive a response. * A binary digit (bit) is the minimum unit of binary information stored in a computer system. A bit can have only two states, on or off, which are commonly represented as ones and zeros.


Causes of Network Latency

Distance 
Latency can be caused by an excessive distance between the server/system making the request and the one that responds to it.

Bandwidth & Network Congestion Network 
congestion happened when there’s a lack of sufficient bandwidth to handle the existing amount of traffic, causing delays to the transmitted data and increasing latency.

Hardware Misconfigurations & Malfunctions 
The check of hardware operation & configuration can be crucial in detecting latency causes. Malfunctioning or misconfigured equipment can lead to mis-matched connections between systems, which can add latency. 

End-User issues 
Network problems might appear to be responsible for latency, but sometimes excessive latency is the result of the end-user device being low on memory or the processing power needed to respond in a reasonable timeframe.

Physical issues 
The physical medium used for communication (wires, fiber, wireless) can also be a source of latency. Cables can become damaged and wireless signal paths can become obstructed leading to loss of data or increased latency.


source : https://broadbandusa.ntia.doc.gov/sites/default/files/2022-12/Introduction_to_Broadband_and_High_Speed_Internet_FINAL_0.pdf