Which modulation scheme is used in gsm

What should be the optimum order of PLL in the carrier phase tracking loop? What is the maximum data rate that can be transmitted using a QPSK modulation with a roll-off factor of 0. The voice channels use 64 kbps PCM coding. The no. Quadrature multiplexing is.

Then the modulation is termed as. The bit rate of a digital communication system is 34 Mbps. The modulation scheme is QPSK. The baud rate of the system is.

Suggested Test Series. Suggested Exams. More Communication Systems Questions Q1. By altering the number of different phase states which can be adopted, the data speeds that can be achieved within a given channel can be increased, but at the cost of lower resilience to noise an interference.

Using 8-PSK, the rate at which symbols are sent remains the same. However each symbol now represents three bits instead of one. This means that the actual data rate is increased by a factor of three. This means that there is an increased risk of any of the symbols being misinterpreted, especially in the presence of interference or noise.

This occurs because it is more difficult for the radio receiver to detect which symbol it has received. To overcome this, additional error coding may be required to protect against the possibility of errors. However increased levels of error protection require additional data to be sent and this reduces the data throughput of the required data. It is a primary requirement that the evolutionary technologies are able to all operate on the same network.

This ensures the service offered to existing customers using older phones along with those paying additional rates for the premium EDGE services. Although originally designed for operation in the MHz band, it was soon adapted for MHz. Over the years, the versatility of GSM has resulted in the specifications being adapted to many more frequency bands to meet niche markets.

At the time of the original system design, this rate compared favourably to those available over fixed connections. However, with the passage of time, fixed connection data rates increased dramatically. In the course of the next few years, the General Packet Radio Service GPRS was developed to allow aggregation of several carriers for higher speed, packet-switched applications such as always-on internet access. The first commercial GPRS offerings were introduced in the early s.

Meanwhile, investigations had been continuing with a view to increasing the intrinsic bit rate of the GSM technology via novel modulation techniques. The standard GSM T M circuit-switched connection offers a data rate much too low for sophisticated web browsing and the transfer of large files, and as early as 3GPP Release 96 of the GSM specifications it was realized that a significant increase in speed could be obtained by aggregating two or more channels into a single, grouped, circuit-switched connection.