Introduction to Broadband Technologies

The market of the broadband technologies is expanding day by day and some of its most common applications include voice, video and data communication, multimedia streaming, interactive gaming, real time video conferencing and the broadcast TV.  Over the recent years the internet and intranet applications have evolved, which resulted into the increasing demands for the higher bandwidth.

Licensed Frequency: These are licensed bands, meaning that individual companies pay a licensing fee for the exclusive right to transmit on assigned channels within that band in a given geographic area. For example, CBS, ABC, and NBC local affiliate stations may be licensed to operate on VHF channels 10, 6, and 3, respectively.

Licensing is a way of ensuring that wireless operators do not interfere with each other's transmissions. Without licensing, interference would garble both transmitters' signals, preventing decent reception. With licensing, the only place where interference occurs is usually at the outer edge of the license-holder's assigned coverage area. However, licensing would be very impractical for certain uses, like communication between your cordless handset and base unit, or interaction between your wireless keyboard and PC.

Links operating in the 6,11,18, & 23GHz bands can have distances ranging from 3 to 50 miles and a maximum of up to 300Mbps per link. 

Lightly Licensed Frequency: Lightly licensed frequency bands are somewhat of a hybrid of the other two types.  An entity must register with the FCC and pay a nominal fee before using any equipment operating in the band.  Although registration is required, it does not grant an exclusive right to use that frequency in any particular location.  Users must still work with each other to mitigate any potential interference issues.
 

Point-to-Point wireless systems connect just two sites together.  They are generally used when relatively few, fixed locations need to communicate, but a high data throughput is needed, and reliability is critical.  Point to point wireless can be a very cost effective alternative to fiber or T-1 based services from the phone company.  Distances can range from a few hundred feet to over 60 miles.  The distance capability depends on frequency, antenna size, tower height, and radio power.  Data throughput rates range from about 5Mbps to 1Gbps.
 

 WLAN Multipoint

Multipoint wireless systems are systems where multiple ‘client’, or subscriber radio devices communicate with a single, central radio, commonly called an Access Point or Base Station.  Multipoint systems are used where multiple sites or devices in an area need to communicate.  Cellular, WiMAX, and Wi-Fi wireless LANs are examples of multipoint systems.  The nature of multipoint systems with multiple remote devices sharing access to the central radio makes the method of how this sharing occurs a key factor in how the system performs.

Now imagine that you are trying to talk to two different people, one on your cell phone and the other on your office phone, so the two you’re talking to cannot hear each other.  Without your intervention, the two will talk at the same time and you won’t be able process what they are saying.  You will have to tell them when they can talk.  Outdoor multipoint wireless systems operate in this manner.  The remote subscribers cannot ‘hear’ each other and if they worked like Wi-Fi, they wouldn’t work very well if many of the remotes have much data to send.  With true outdoor multipoint systems, such as WiMAX & Motorola Canopy, the client radios must first make a request and have it acknowledged by the Access Point before sending data – Similar to raising your hand before talking in a big group.
 

 Mesh Networks

A wireless mesh network is a communications network made up of radio nodes in which there are at least two pathways of communication to each node. The coverage area of the radio nodes working as a single network becomes a mesh cloud. Access to this mesh cloud is dependent on the radio nodes working in harmony with each other to create a radio network.

A mesh network is reliable and offers redundancy. When one node can no longer operate, the rest can still communicate with each other, directly or through one or more intermediate nodes. Wireless mesh networks are self-healing networks, meaning the network can still operate even when a node breaks down or a connection goes bad. As a result, a very reliable network is formed. This concept is applicable to wireless networks, wired networks, and software interaction.