Wi-Fi technology is a technology used for transmitting a signal using the 802.11 specifications works a lot like it does with a basic Ethernet hub: They’re both two-way forms of communication, and they both use the same frequency to both transmit and receive, often referred to a half-duplex. WLANs used radio frequencies (RFs) that are radiated into the air from an antenna that creates radio waves. These waves can be absorbed, refracted, or reflected by walls, water, and metal surfaces, resulting in low signal strength. So because of this vulnerability to surrounding environmental factors, it’s pretty apparent that wire-less will never offer us the same robustness as a wired network can, but that still doesn’t mean we’re not going to use or run the wireless or Wi-Fi.
- The maximum data rate supported by a GSM system is 9.6 kbps. - However there are extensions to GSM standard to improve throughput. - GPRS is one of the extended GSM service. - The extended standards of GSM allows theoretical data rates on the order of 114 Kbit/s, but with throughput closer to 40Kbit/s in practice.
- GPRS provide gross data rate of 22.80 KBPS / time slot - Voice uses only 13KBPS/ time slot and the rest is consumed by Error Correction Code - Error connection code is utilized for detecting and correcting the transmission errors - As voice is compressed, the usage of Error connection code is mandatory
- GPRS uses 2.5 generation of GSM signals - The radio interface is the same that of GSM - GPRS uses 900 / 1800 Mhz, frequency band and GMSK modulation - The bit rates are EGPRS, similar to EDGE - Separate hardware and ports need to be added and availed.
Basically there are many standards of Wi-Fi in the industry but some popular of them are 802.11a, 802.11b, 802.11g/n. With the support of these Wi-Fi protocols we can communicate/interact among the devices at the speed of 5Ghz to 2.4Ghz dual band communication.
If we have Wi-Fi nic card so firstly we have to install their drivers and after installation if we have Wi-Fi access point then we can see the signal strength in the right corner below just open that and find the access point to connect, if access point is configured with the security, type the key to connect and enjoy the service.
Wi-Fi is technically referred to as the 802.11 protocol. Over time, Wi-Fi has improved, giving rise to different variations of the protocol.
802.11a – This version operates at 54Mbps. It is considered as the favorite wireless LAN protocol for IP telephony.
- Overcrowding is relieved in existing systems with radio spectrum - Bandwidth, security and reliability are more - Provides interoperability among service providers - Availability of fixed and variable rates - Support to devices with backward compatibility with existing networks - Always online devices – 3G uses IP connectivity which is packet based - Rich multi media services are available
Disadvantages of 3G:
- The cost of cellular infrastructure , upgrading base stations is very high - Needs different handsets. - Roaming and data/voice work together has not yet been implemented - Power consumption is high - Requires closer base stations and are expensive - Spectrum-license costs, network deployment costs and handset subsidies subscribers are tremendous.