This technique is most widely used for digital cellular radio. A GSM system has 4. Each channel has different uplink and downlink frequencies. Developed in Europe, GSM is a second generation 2 G cellular system which uses digital modulation and network level architectures and services. Commercial services of GSM started in mid It can handle both, voice and data traffic, the voice waveform being digitally encoded before transmission.
Data transmission and reception at bps speed. Each channel is time shared between 8 subscribers in TDMA scheme with frame duration of 4. Radio transmission on both forward and reverse link are made at channel data rate of But, user data is sent at a maximum rate of Every time slot TS has Each time slot has duration of Each mobile equipment or unit is uniquely identified by the International Mobile 6.
The interface comprises of traffic and control channels. Um interface is also called radio or air interface. Abis interface may be a modem, radio or optical fibre. This interface is defined by GSM equipment manufacturer. It performs interleaving and deinterleaving. It enables full duplex communication to MS. It handles radio-channel setup, frequency hopping and handoffs. It controls the operation of BTSs. NSS includes data bases required for subscribers and mobility management as well as switching and routing.
It connects the subscriber with another subscriber or PSTN. It also performs the function of call setup, supervision and release along with digit collection, translation, billing information collection, registration, echo cancellation and local updating. Any call made by subscriber first comes to MSC and then it is routed to the desired subscriber.
These are physically connected by leased lines or microwave links. HLR database is of two types- Dynamic and Permanent. An IMEI is marked as invalid if it has been reported stolen or is not approved. It is a self contained unit for transmitting and receiving signal for mobile communication.
On the other hand, no shelter is required for outdoor BTS and Air condition is also not a must. Floor is made up of 19mm thick marine plywood and is covered with PVC antistatic flooring. MS tube is reinforced inside floor panel for higher floor load capacity. Secondary slanting roof is provided to protect primary roof from direct sunlight and rainwater.
Door is fixed with heavy-duty hinges, and is equipped with hydraulic closer and three way locking arrangement. These are high quality coaxial combiners available in various configurations covering full octave bands from MHz to 2.
All have N female terminations, can handle 10 watts of power and provides 20dB of isolation between ports. Antenna Network Combiner ensures the combiner and duplex functions. TRAU is a data rate conversion unit. However, many services advertised as 3G provide higher speed than the minimum technical requirements for a 3G service.
Recent 3G releases, often denoted 3. Services advertised as 3G are required to meet IMT technical standards, including standards for reliability and speed data transfer rates.
Thus users sold 3G service may not be able to point to a standard and say that the rates it specifies are not being met. By allowing the User Equipment to authenticate the network it is attaching to, the user can be sure the network is the intended one and not an impersonator. In addition to the 3G network infrastructure security, end-to-end security is offered when application frameworks such as IMS are accessed, although this is not strictly a 3G property.
It provides services midway between 2G and 3G. Hence, it is also termed as 2. The data transfer takes place at the rate of kbps. GPRS usage is typically charged based on volume of data transferred, contrasting with circuit switched data, which is usually billed per minute of connection time. Multimedia messaging service MMS 3. Internet applications for smart devices through wireless application protocol WAP 4. The TCP handles any packet loss e. It provides nearly three times faster speeds than the outdated GPRS system.
The theoretical maximum speed is kbps for 8 timeslots but it is typically limited to kbps in order to conserve spectrum resources. EDGE meets the requirements for a 3G network but is usually classified as 2. EDGE can be used for any packet switched application, such as an Internet connection. If the operator already has this in place, which is often the case today, the network can be upgraded to EDGE by activating an optional software feature.
EDGE produces a 3-bit word for every change in carrier phase. This effectively triples the EDGE, like GPRS, uses a rate adaptation algorithm that adapts the modulation and coding scheme MCS according to the quality of the radio channel, and thus the bit rate and robustness of data transmission.
It introduces a new technology not found in GPRS, Incremental Redundancy, which, instead of retransmitting disturbed packets, sends more redundancy information to be combined in the receiver. This increases the probability of correct decoding. This means it can handle four times as much traffic as standard GPRS.
It is the hardware that is connected to the mobile phone network that communicates directly with mobile handsets.
As in In this type of cellular network, the mobile devices cannot communicate directly with each other but have to communicate with the Node B. Soft handovers make use of this effect. Power requirements on Node Bs and user equipment UE are much lower.
A full cell site has a cabinet, an antenna mast and actual antenna. An equipment cabinet contains e. A Node B can serve several cells, also called sectors, depending on the configuration and type of antenna. The RNC carries out radio resource management, some of the mobility management functions and is the point where encryption is done before user data is sent to and from the mobile.
An RNC also control the power of a NODE B. The logical connections between the network elements are known as interfaces. Iu interfaces carry user traffic such as voice or data as well as control information see Protocols , and Iur interface is mainly needed for soft handovers involving 2 RNCs though not required as the absence of Iur will cause these handovers to become hard handovers.
The physical interface to a base station will be such that the Iub capacityfrom a given base station has some discreet value. Of course, the user traffic is likely to be asymmetrical, and weare likely to find that the downlink traffic is greater than the uplink traffic. The actual Iub transmission facilities, however, will be symmetrical. Inother words, if there are 2 Mbps capacity on one direction, there is also 2Mbps in the other direction.
Therefore, when dimensioning the Iub, we needonly to consider the user traffic in one direction—the direction of greaterdemand. This will usually be the downlink direction. There are various types of OMCs depending on the functionality: i. This includes expansion of network, techniques to boost capacity, lowering interference and increasing quality in the network. Macro cell planning is emphasised.
Planning is the process of assigning frequencies, transmitter locations and parameters of a wireless communications system to provide sufficient coverage and capacity for the services required. The RF plan of a cellular communication system has two objectives: coverage and capacity.
Capacity relates to the capability of the system to sustain a given number of subscribers. Capacity and coverage are interrelated. To improve coverage, capacity has to be sacrificed, while to improve capacity, coverage will have to be sacrificed.
Planning consists of four stages1. It uses the RF Link Budget along with a statistical propagation model. The statistical propagation model does not include terrain effects and has a slope and intercept value for each type of environment. This fairly simplistic approach allows for a quick analysis of the number of sites that may be required to cover a certain area. Estimated Number of Sites is the output produced at this stage.
Automatic planning tools are often employed in The propagation model takes into account the characteristics of the selected antenna, the terrain, and the land use and land clutter surrounding each site.
Since these factors are considered, this propagation model provides a better estimate of the coverage of the sites than the initial statistical propagation model. This process is required in the deployment of the system or in determining service contract based coverage. This phase starts from initial network deployment and involves collecting measurement data on a regular basis that could be via drive testing or centralised collection. The data is then used to plan new sites or to optimize the parameter settings e.
Electrical Tilt, Mechanical Tilt, Azimuth etc. Besides that there are various key performance indicators which have to be constantly monitored and necessary changes proposed in order to keep KPIs in agreed limits with the mobile operator. Gone are the days of being tied to a desk or staying close to a landline phone to avoid a missed call.
Communication, entertainment, exercising and travel are merely a few lifestyle improvements made possible with mobile technology. Mobile phones are the most obvious mobile devices and are available to millions and millions of people. Callers are almost instantly connected to each other through a series of cellular connections that reach even to the most remote areas of the world.
These cellular connections are not only for mobile phones. Laptops and PDAs share data across the cellular system. In fact, some Smart phones act as modems for laptops. Expensive connection to the internet or to a network is not always necessary. Uplink and downlink traffic can have different modulation schemes. Nature is obstinate. Despite all our tricks, there are certain things, which are impossible to get. Considering that the real bandwidth is much lower than theoretical, we shall take the above estimate of 5.
But you shouldn't think that the bandwidth at 30 km away from the access point will also be 5. So a modulation level is reduced, fewer bits are transmitted in a single symbol. We should also take into account that a higher-frequency signal is better absorbed by the air. According to some estimates, you can get its maximum bandwidth Thus, we cannot say that the communication range is a forte of this or that technology.
But we should note that WiMAX base stations can connect to each other even when they are not in the line-of-sight. The true forte of HSDPA is the fact that this technology is initially intended for lots of simultaneous users, while WiMAX is limited to dozens, or hundreds terminals at best. Moreover, experts forecast serious problems for WiMAX in corporate networks, when the number of their users grows. If all users suddenly decide to download a large file from Internet, it will certainly affect data rates.
First of all it's because WiMAX does not have many frequency ranges yet. Both technologies have practically the same capacities for transmitting multimedia data. HSDPA does not provide any additional security functions. Data encoding for different users, typical of all CDMA standards, works better than any cryptographic algorithm, but not if an intruder is in a base station or somehow gets its channels code like special agents.
It will certainly please corporate users, who want to keep their data in secret. But this secret will not hold forever, as there are no security measures that cannot be broken.
It's impossible to appoint a certain favorite among these two technologies. Both of them have fortes and drawbacks. So it has already taken root.
But it's always good when there are two competing technologies on the market. On one hand, this situation stimulates technical progress; on the other hand, it always leads to the reduction of prices for consumers - it's good, isn't it?
Write a comment below. No registration needed! Article navigation:. Sandy Bridge. All rights reserved. Convergence or War of the Worlds? Picture 1. Future development of data transfer technologies click to zoom. Sergei Lurie archont ixbt. Oct 08, Oct 04, Oct 03, Essentially, it is necessary to update the software of the GSM base station and optionally to replace individual components.
If GPRS is activated, only virtually, there is a permanent connection to the remote site the so-called always-on mode. Only when real data is transmitted, the radio room is occupied, otherwise it is free for other users. Therefore, no permanent radio channel needs as with CSD reserved for a user to be. GPRS bills are therefore mainly dependent on the quantity of data transferred rather than connect time. However, this is also dependent on the particular contract terms with the operator.
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