Significance Of Wireless

Significance Of Wireless Connectivity

Nowdays  when it is the era of IT evolution , technology is emerging so fast that we are getting almost everything that we want .

Applications of wireless connectivity has increased from just internet connectivity to much more.

Following are the few examples .

·        Bluetooth – You can connect mobile to PC , Mobile to Mobile , tablets etc to transfer data over wireless to the devices

·        Bluetooth for wireless mouse or keyboard .

·        Short-Range WiFi for showing presentations over the screen without physically connected to the projector.

·        Wireless connectivity for CCTV monitoring over the large distance.

 

There are much more applications of wireless connectivity that we can ever thought of , In short we can say that wireless connectivity can be the easy , cost effective and easy to maintain alternative for the wired connectivities.

Calculation Of EIRP

EIRP stands for Effective isotropic radioated power , the power which is radiated out from antenna .Every country has different EIRP limitations.

Power calculation 10s and 3s rule will play important rule in EIRP calculation, For every 3db increase in power the transmit becomes double , to calculate EIRP add all gains and deduct losses from radio to antenna .

let us say radio has a tx power 25dbm and it is attached to the antenna woth the gain 3 dbi .
25 dbm in mw will be approx 250 mw and with no other losses , the EIRP i this case will be 25+3 = 28dbm or 500mw.

If there is some losses in the physical connections lets say 1db then EIRP will be 27dbm.

To limit the EIRP the transmit power of radio and antenna gain has to be adjusted.

TRANSMIT POWER CALCULATIONS

For every 3 db increase in power the equivalent power in mw gets doubled i.e if initial Tx power is x dbm equivalent to y mw and if we increase the power to (x+3)dbm then it will be equivalent to 2y mw it means the Tx power doubles in mw for every 3db increase in power and similarly the Tx power becomes half in mw for every 3db decrease in power.

Similarly power becomes 10 times in mw for every 10 db increase and becomes 1/10 in mw for every 10 db decrease.

As the above calculations are valid only for 10db and 3 db it is called as rule if 3s and 10s.

Note : Above calculations is very useful when designing the wireless network but for product and circuit designing logarithmic calculation is best.

Importance of Lat-Long GPS Co-ordinates.

Lat/Long are the very basic components when we talk about point to point wireless installation.

With lat long we can find out the exact air distance of the link , We can get the elevation profile with google earth , we can the alignment direction of the radios from each direction.

The best way to plan for any point to pint link is to do a LOS path survey , when planning with the microwave frequencies , We must have a clear LOS to give a reliable link connectivity.

Then there are other things line link budgeting , Site readiness etc but importance of lat long cannot be ignored.

Beamforming

Beamforming is the smart antenna technology  . Beamforming transmits power only in desired direction i.e the power is directed in the direction of user.

In point to multipoint scenario it saves the unnecessary transmission of power.

Interference due to multiple path i.e ISI can be avoided by using beamforming , As antenna transmitsin the direction of user so there is no other path of radio transmission to that user , so no multiple path and so no multiple path interference.

OFDM is also a way to avoid multiple path interference . OFDM infact takes the advantage of multiplepath interference.


Please go through OFDM multiple path mitigation capability to understand about its working.

Fixed and Mobile Wi-max

Fixed Wimax ( Worldwide Interoperability for microwave access) is IEEE 802.16d standard , Fixed wimax means that CPE has to be fixed at one place and latched to the base station from which it has to communicate . In fixed Wimax base station and CPE , both are installed outside that is both are outdooe device . one CPE is associated with one base station only and one base station can be associated with more than one CPE's.

Mobile Wimax is 802.16e standard . In mobile Wimax , Base station base station is fixed but cape can be movable , here CPE can be the outdoor device or it can be dongle.

As CPE moves from coverage range of one base station to another base station , The CPE can be latched with another base station without any communication break , this process is known as handoff , here CPE compares the signal strength between the two base station and associates itself with the base station having strongest signal strength when the weaker signal strength falls below the threshold level , The process of handoff is controlled by ASN ( Access service network) i.e ASN is responsible for handoff without any communication  break.

OFDM V/s OFDMA

OFDM stands for Orthogonal Frequency Division Multiplexing . OFDM is one of the feature of Wimax 802.16d standard developed for fixed wimax.

OFDM is used in point to point connectvity . For two way data transmission OFDM is used with TDD (Time Dicision Duplexing)

OFDMA stands for Orthogonal Frequency Division Multiple Access. OFDMA is point to multipoint version of OFDM . OFDM is multiplexing and OFDMA is multiple access where multiple CPE's can be connected with same base station.

In OFDMA fixed wimax point to multipoint connectivity , uplink transmission ( CPE to base station ) can be OFDM because one CPE can be conneced to one base station only , but in downlink transmission ( Base station to CPE) is OFDMA as one base station is connected to many CPE's.