Wireless Network Engineering: Digital And Analog Essay

Question:

Describe about the Wireless Network Engineering for Digital and Analog.

Answer:

1: Comparison Between analog signals and digital signals:

Particulars

Analog signals

Digital signals

Signal

It is a continuous signal which represent physical measurement

It is a discrete signals which represent digital modulation

Waves

Sine waves representation

Square waves representation

Representation

Continuous range of values

Discontinuous range of values

Technology

Record waveforms

Limited number of records

Transmission of data

Noise can occur deterioration in the completion of read and write cycle

Noise can occur without deterioration in the completion of read and write cycle

Response given to noise

Reduce the accuracy

Analog response are generated

Flexible

Implementation of hardware is not flexible

Implementation of hardware is flexible

Uses

It is best suitable for analog devices

It is suitable for devices of digital electronics

Bandwidth

It consumes less bandwidth

It consumes more bandwidth

Transmission of radio waves using antenna:

The radio waves are usually used for the transmission of sounds and pictures. The modulated carrier wave is generated by the oscillator circuit transformer which is then applied to the antenna for converting the electrical signals to electromagnetic waves. “This transmission takes place at the speed of light” (Dan, 2008). The receiving antennas at receiver site receive the modulated signals in the electromagnetic wave and then transform it into electrical waves.

2: The multiplexing methods are described below:

FDMA:

FDMA stands for frequency division multiplexing access which makes use of fundamental technique of dividing bandwidth or single channel into multiple channels. Each individual channels have single spectra for the transmission of data. In the transmission of the data, the linear mixing of the subcarrier takes place.

TDMA:

TDMA stands for time division multiplexing access which is used for dividing the single channel into number of time slots or bands. “Every time slot is capable of transmitting of one byte of data” (Shacklett, 2012). The transmission of digital segment takes place in sequential order. This is the best method used for signals having slow voice data, compressed video, and the data which requires high speed transmission. The global system of mobile communication technology is based on the time division multiplexing access.

CDMA:

CDMA stands for code division multiplexing. It is based on the technique of digitization. It make use of direct sequence spread spectrum which can be accomplished by digitizing the analog signal and transmit it by using wider bandwidth. The chipping codes of 5MHz allow the multiple users to share the data at the same time having common bandwidth. The technology uses XOR circuit for chipping the signal at higher frequency. The XOR circuit is also used for sending digitized and compressed signals in serial order. CDMA employed the technique of Spread spectrum.

Future Technology:

CDMA is the dominant technology in the future of wireless technology because it sends the compressed voice at 3.84 Mbit / sec. The chipping codes of 5MHz allow the multiple users to share the data at the same time having common bandwidth.

3:

The sensitivity of receiver and sender predicts the quality of wireless transmission. The quality of the transmitted signal can be improved by improving the sensitivity of the receiver. By improving the characteristics of antenna like frequency, impedance, ability of transmitting and receiving signals, polarization of the antenna, pattern of the antenna radiation, short distance reception should be used, and installation of the antenna should be simplified by dividing the receiving end. “For the installation of the antenna, it is required to use minimum cable length and the connection point used between two antennae” (Mohammed, 2014).

The size of the antenna can depends on the factors like distance between the sites, the Fresnel zone, and objects placed in the path.

Distance of Wireless Link

Approximate value of Fresnel zone

Approximate value of earth curvature

Size of the antenna

1

2

3

4

3

23

4

27

5

30

5

35

8

40

8

48

10

44

13

57

15

55

23

83

20

65

50

115

25

72

78

150

4:

ZigBee makes use of IEEE standard of 802.15.4specification for the implementation of physical layer and MAC layer.

Star Topology:

It is the combination of coordinator and end devices. The communication between the end devices and coordinator takes place by doing exchange of the data packets.

Advantage:

The nodes can easily be connected to one another

Disadvantage:

The operation of the topology depends on the working structure of the coordinator. No availability of alternative path

Tree topology:

In this, the central node is called as root by which the coordination of other end devices takes place. The end nodes are called as children. In the complete formation of the structure only router and coordinator can have children.

Advantages:

It offers expandability of the network

Disadvantages:

“The disabling of one parent results into breakage of communication with other devices” (Thomsons, 2012). The two nodes which are in close relationship cannot communicate with one another.

Mesh Topology:

It is the combination of coordinator, many routers, and end devices. It is a multi-hop network which passes packet through multi-hop.

Advantages:

“It helps in eliminating the dead zone” (Vallabh, 2014). The communication can takes place with any destination node.

Disadvantages:

It results into greater overhead. It uses complex routing protocol.

5: Protocol Layer implementation for Wireless HD:

The layering model for wireless HD is divided into four functional layer which are named as PHY layer, Mac sub-layer, Adaptation sub-layer, and station management entity. The AVC protocol and A/V packetizer are used in the adaptation sub-layer. “The four function entities of the layered model provides services like transmission of high rate data, services related to low data rate, and lastly, the service of management” (Marco, 2015). The HR protocol data unit consist of information like identification of beam tracking, use of UEP mode for coding, scrambler initialization, and spatial stream for transmission of packet. The LRP works in the same bandwidth of HRP. The WVAN is the super-frame which is used for Mac layer for the transmission of time slot. A random access time block is used for transmitting data packets.

The layered model for wireless HD is shown below:

References:

Marco, P. (2015). Protocol design and implementation of wireless sensor network (1st ed.). Retrieved from

Mohammed, D. (2014). WiFi Antenna installation best practices design guide (1st ed.). Retrieved from

Shacklett, M. (2012). Multiple Access Technique (1st ed.). Retrieved from

Thomson, K. (2010).Zigbee wireless sensor network and their application (1st ed.). Retrieved from

Vallabh, V. (2014). IEEE 802.15.4 and ZigBee: A conceptual study (1st ed.). Retrieved from

Dan, L. (2008). Cooperative Analog digital signal processing (1st ed.). Retrieved from

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