Facts about cellular communication
3G, UMTS, WCDMA, GSM, 4G och LTE. We explain the concepts and explains the technology.
GSM networks are now getting on in years but with several operators upgraded and, indeed, completely replaced with new platforms. GSM is also known as 2G, second generation mobile telephony. In Europe, typically two different frequency bands for GSM: GSM900, GSM1800.
GSM uses a technology that lets you assign each cell a number of telephone channels or data channels which communication takes place over. Each channel is in a frequency band is 200 kHz wide and in this band divide up these channels so that they have their own, small, time-frame as speech or data transmission is in. It uses different coding algorithms for transmitting audio or data between the terminal / phone to the base station, depending on the algorithm (and capacity utilization in the cell), you get different compression ratio of the number transferred.
In the case of data transmission is done in a slightly different way in which channels are added at each other and this way you get a higher speed of data transfer. Data transfer takes place asynchronously. They talk about Up-Link (Terminal - Base station) which is always a lower speed than the Down-link (top ten - Terminal). The reason is simple, the need is usually the user to download more data than they upload. Notice that this is not the telephone channels but only data channels!
For mobile Internet using GSM two different data services, GPRS or EDGE. The difference is considerable current speed on these technologies. EDGE is called often 2.5G technology, because the speed of data transfer, which is nearly in range with the first 3G network data rates.
GSM is often a good coverage when there is extensive base stations and reaches relatively far with their signals on the 900MHz band. Problems that may arise with GSM is of course a low speed of data transfer but also the audio quality of the voice may become inadequate when the power is getting tight in a base station. Problems of this nature are rare in 3G networks.
3G (also known as UMTS or WCDMA)3G networks offer both telephony and mobile Internet. 3G available today that two standards WCDMA andCDMA2000. The latter technique is quite narrow and are primarily in the U.S. and Asia, but also individual networks in Europe. The term 3G mean in Europe we usually WCDMA-based cellular networks. 3G has various services such as telephony, mobile Internet, SMS, MMS, etc. Usually nytjar 3G 2.1 GHz bands. From 2011 to begin even 3G will be delivered at 900MHz bands, ie the same frequency bands GSM900. The 1800MHz-band GSM uses will most likelynot be used for 3G but for 4G.Mobile phones in the 3G network to communicate with one or more base stations. The concept of NodeB is what you call the technical broadcasting equipment at base stations. Each base station is usually between 1-4st frequenciesto transmit and receive on. These frequencies are 5 MHz wide and called UARFCN. Each base station is thentypically 1-3 antennas which is called cells. Each cell has an individual sequence number (512 possible), called SC(Scrambling Code). When several SC of a mobile phone is seen as an equally good quality broadcast the same information from all these cells. The mobile adds thus signals together and get a total received signal thus has lessprobability of error.4G (LTE)The technique that usually goes under the notion that the operators called 4G is a technology called LTE (LongTerm Evolution). 4G as a concept is a bit misleading, but we will not go into it here. As the name suggests is an evolution of LTE 3G/UMTS/WCDMA networks.The big difference is simply expressive three factors:
The frequencies of LTE is different from 2G and 3G. In Europe, LTE will be offered at the following frequencyrange: 800MHz, 900MHz, 1800MHz, 2300MHz and 2600MHz. Different operators based LTE in different frequency bands. The earliest 4G networks built in the 2600MHz band and it is still happening. Now begins a few operatorscomplete the 4G network of 800 and 900MHz bands. Soon it will also be true later 1800MHz 2300MHz bands to offer4G.
- Radio interface in LTE differ significantly from 3G. This is to achieve the high speeds that today theoretically is more than 300Mbit / s. The future will offer speeds of over 1Gbps / s (!) And that communication takes place in parallel across multiple frequency bands.
- The technology is "All-IP" (IMS - "IP Multimedia Subsystem"). This means a big change in the entire system architecture and all communication is done using TCP / IP, unlike 2G and 3G.
- LTE offers only various types of data networks with different speeds and priorities. Of course, the voice will be offered in LTE but note that it then deals with IP telephony and thus made all telephony with the support of such SIP.
CDMA2000/450 and TETRA
HIPS Ltd currently has no amp in stock for TETRA or CDMA450. However, we can through our vendors offer a variety of amplifiers and antenna til these systems. Contact HIPS Ltd for further information
Amplifier and signal strength
With an amplifier installed, you will get better signal strength, which eliminates problems such as call "cut", missed calls, telephone / modem transmitting at maximum power, and often get even better performance on the mobile internet.
The amplifiers get a signal outside and moves the signal indoors, where they often experience a significantly reduced signal strength due to the building's construction, walls, ceilings, windows, etc. as well as UMTS GSM amplifier is of "Lågeffektstyp". It takes an existing signal outdoors, leading into the signal indoors and reinforces the low (around 10-20dbm). You then get about the same, or slightly stronger, signal strength indoors and outdoors.Note that the signal emitted from the amplifier is not harmful in any way but is very comparable to a wireless phone or a wireless LAN.
The advantage of lågeffektsförstärkare is to risk not getting too much amplification of radio signals that it may cause interference for your neighbors.
Signal strength in 3G (UMTS / WCDMA)
Signal strength is measured in the UMTS network on the strength of the RSCP signal. Each cell has a pilot channel that mobile phone use to sync against. This pilot channel is called CPICH (Common Pilot Channel) and always has the same signal strength. When you want to measure out a radio signal to determine the coverage and quality in a UMTS network is based on CPICH. Received signal strength (radio energy) from a cell called RSCP (Received Signal Code Power). RSCP is the energy you want to reinforce to your mobile phone to have a good and robust communications. Another important parameter is the signal quality called Ec / No. This is in addition an important variable to ensure the quality of calls and data transfer is used the signal quality in a UMTS / WCDMA calculate handover between base stations and roaming to GSM. Received quality of the radio signal from a cell known as Ec / No. Signal quality is very important and will determine how easily the mobile phone has to read the signal as a radio base station sends. For 3G (WCDMA) is the instantaneous load, ie. the number of people who have both an on-going mobile call to the cell you are currently connected to, directly related to the Ec / No. This means that the Ec / No change over time so that in Ec / No deteriorate when many simultaneously calls and then have improved while calling.
Signal strength in 2G (GSM)
GSM belongs to the so-called second-generation mobile communications systems. 2G and 3G is different to the one-piece but has a similar technical solution with the base station, frequency and cell. GSM radio base station is called BTS, and through this to be all connected phones one or several frequencies. Temporal frequency is divided into time slots. In GSM divided thus resources among users in time and frequency. Transmission and reception is cyclic. Each cell has a pilot channel that mobile phone use to sync against. This pilot channel is called, BCCH (Broadcast Control Channel), as mobile phones sync to and receive information from. The received energy and decoded signal in the GSM network is called RxLev. Received signal strength (radio energy) from a cell called BCCH. RxLev is the absolute energy received by the mobile phone.
Roaming between UMTS and GSM
Roaming is a technical term that describes the technical ability of a terminal (mobile phone) to switch between two base stations of different networks without being disconnected. Users can have their terminals, switches between UMTS and GSM networks, and this is controlled by the configuration of telecom networks. Coverage between the different networks vary so calls can be switched between UMTS / GSM depending on radio coverage, signal quality, and in addition the operator has chosen to configure their specific networks. Usually it does not address the user that during active call moves between these techniques.
As an example: A user who is in a part of a UMTS network with a very bad signal / quality ratio switched to GSM, provided that the operator has the kind of technology available. The user will remain on the GSM network for a shorter or longer period. Return to UMTS takes place only when the network operator's pre-defined thresholds are met / exceeded or depending on the signal / quality ratio of GSM and UMTS is. Roaming is completely controlled by the operators and are thus dependent on a combination of pre-defined thresholds and / or signal / quality ratio in the different networks.
HIPS Ltd has a good knowledge of the different techniques and how you can best utilize them. Of course, we can help by suggesting solutions that suit you best. We can also offer full custom amplifier.