General Packet Radio Service
Encyclopedia
General packet radio service (GPRS) is a packet oriented mobile data service on the 2G
and 3G
cellular communication system's global system for mobile communications
(GSM). GPRS was originally standardized by European Telecommunications Standards Institute
(ETSI) in response to the earlier CDPD and i-mode
packet-switched cellular technologies. It is now maintained by the 3rd Generation Partnership Project (3GPP).
GPRS usage charging is based on volume of data, either as part of a bundle or on a pay-as-you-use basis. An example of a bundle is up to 5 GB per month for a fixed fee. Usage above the bundle cap is either charged for per megabyte or disallowed. The pay as you use charging is typically per megabyte of traffic. This contrasts with circuit switching
data, which is typically billed per minute of connection time, regardless of whether or not the user transfers data during that period.
GPRS is a best-effort service, implying variable throughput
and latency
that depend on the number of other users sharing the service concurrently, as opposed to circuit switching
, where a certain quality of service
(QoS) is guaranteed during the connection. In 2G systems, GPRS provides data rates of 56-114 kbit/second. 2G
cellular technology combined with GPRS is sometimes described as 2.5G, that is, a technology between the second (2G
) and third (3G
) generations of mobile telephony. It provides moderate-speed data transfer, by using unused time division multiple access
(TDMA) channels in, for example, the GSM system. GPRS is integrated into GSM Release 97 and newer releases.
, 3G
and WCDMA mobile networks
to transmit IP
packets to external networks such as the Internet
. The GPRS system is an integrated part of the GSM network switching subsystem
.
If SMS over GPRS is used, an SMS transmission speed of about 30 SMS messages per minute may be achieved. This is much faster than using the ordinary SMS over GSM, whose SMS transmission speed is about 6 to 10 SMS messages per minute.
When TCP/IP
is used, each phone can have one or more IP address
es allocated. GPRS will store and forward the IP packets to the phone even during handover
. The TCP handles any packet loss (e.g. due to a radio noise induced pause).
Class A: Can be connected to GPRS service and GSM service (voice, SMS), using both at the same time. Such devices are known to be available today.
Class B: Can be connected to GPRS service and GSM service (voice, SMS), but using only one or the other at a given time. During GSM service (voice call or SMS), GPRS service is suspended, and then resumed automatically after the GSM service (voice call or SMS) has concluded. Most GPRS mobile devices are Class B.
Class C: Are connected to either GPRS service or GSM service (voice, SMS). Must be switched manually between one or the other service.
A true Class A device may be required to transmit on two different frequencies at the same time, and thus will need two radios. To get around this expensive requirement, a GPRS mobile may implement the dual transfer mode (DTM)
feature. A DTM-capable mobile may use simultaneous voice and packet data, with the network coordinating to ensure that it is not required to transmit on two different frequencies at the same time. Such mobiles are considered pseudo-Class A, sometimes referred to as "simple class A". Some networks support DTM since 2007.
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USB 3G/GPRS modems use a terminal-like interface over USB 1.1, 2.0 and later, data formats V.42bis, and RFC 1144 and some models have connector for external antenna
. Modems can be added as cards (for laptops) or external USB devices which are similar in shape and size to a computer mouse, or nowadays more like a pendrive.
(APN). The APN defines the services such as wireless application protocol
(WAP) access, short message service
(SMS), multimedia messaging service
(MMS), and for Internet
communication services such as email
and World Wide Web
access.
In order to set up a GPRS connection for a wireless modem
, a user must specify an APN, optionally a user name and password, and very rarely an IP address
, all provided by the network operator.
; i.e., packet mode communication, which makes it possible for several users to share the same frequency channel. The packets have constant length, corresponding to a GSM time slot. The down-link uses first-come first-served packet scheduling, while the up-link uses a scheme very similar to reservation ALOHA
(R-ALOHA). This means that slotted ALOHA (S-ALOHA) is used for reservation inquiries during a contention phase, and then the actual data is transferred using dynamic TDMA with first-come first-served scheduling.
at different code rate
s and GMSK modulation defined for GSM. The following table summarises the options:
The least robust, but fastest, coding scheme (CS-4) is available near a base transceiver station
(BTS), while the most robust coding scheme (CS-1) is used when the mobile station (MS) is further away from a BTS.
Using the CS-4 it is possible to achieve a user speed of 20.0 kbit/s per time slot. However, using this scheme the cell coverage is 25% of normal. CS-1 can achieve a user speed of only 8.0 kbit/s per time slot, but has 98% of normal coverage. Newer network equipment can adapt the transfer speed automatically depending on the mobile location.
In addition to GPRS, there are two other GSM technologies which deliver data services: circuit-switched data
(CSD) and high-speed circuit-switched data
(HSCSD). In contrast to the shared nature of GPRS, these instead establish a dedicated circuit (usually billed per minute). Some applications such as video calling may prefer HSCSD, especially when there is a continuous flow of data between the endpoints.
The following table summarises some possible configurations of GPRS and circuit switched data services.
and Downlink directions. It is a value between 1 to 45 which the network uses to allocate radio channels in the uplink and downlink direction. Multislot class with values greater than 31 are referred to as high multislot classes.
A multislot allocation is represented as, for example, 5+2. The first number is the number of downlink timeslots and the second is the number of uplink timeslots allocated for use by the mobile station. A commonly used value is class 10 for many GPRS/EGPRS mobiles which uses a maximum of 4 timeslots in downlink direction and 2 timeslots in uplink direction. However simultaneously a maximum number of 5 simultaneous timeslots can be used in both uplink and downlink. The network will automatically configure the for either 3+2 or 4+1 operation depending on the nature of data transfer.
Some high end mobiles, usually also supporting UMTS also support GPRS/EDGE
multislot class 32. According to 3GPP
TS 45.002 (Release 6), Table B.2, mobile stations of this class support 5 timeslots in downlink and 3 timeslots in uplink with a maximum number of 6 simultaneously used timeslots. If data traffic is concentrated in downlink direction the network will configure the connection for 5+1 operation. When more data is transferred in the uplink the network can at any time change the constellation to 4+2 or 3+3. Under the best reception conditions, i.e. when the best EDGE modulation and coding scheme can be used, 5 timeslots can carry a bandwidth of 5*59.2 kbit/s = 296 kbit/s. In uplink direction, 3 timeslots can carry a bandwidth of 3*59.2 kbit/s = 177.6 kbit/s.
The different multislot class specification is detailed in the Annex B of the 3GPP Technical Specification 45.002 (Multiplexing and multiple access on the radio path)
connection in an analog wire telephone network, about 32-40 kbit/s, depending on the phone used. Latency
is very high; round-trip time (RTT) is typically about 600-700 ms and often reaches 1 s. GPRS is typically prioritized lower than speech, and thus the quality of connection varies greatly.
Devices with latency/RTT improvements (via, for example, the extended UL TBF mode feature) are generally available. Also, network upgrades of features are available with certain operators. With these enhancements the active round-trip time can be reduced, resulting in significant increase in application-level throughput speeds.
2G
2G is short for second-generation wireless telephone technology. Second generation 2G cellular telecom networks were commercially launched on the GSM standard in Finland by Radiolinja in 1991...
and 3G
3G
3G or 3rd generation mobile telecommunications is a generation of standards for mobile phones and mobile telecommunication services fulfilling the International Mobile Telecommunications-2000 specifications by the International Telecommunication Union...
cellular communication system's global system for mobile communications
Global System for Mobile Communications
GSM , is a standard set developed by the European Telecommunications Standards Institute to describe technologies for second generation digital cellular networks...
(GSM). GPRS was originally standardized by European Telecommunications Standards Institute
European Telecommunications Standards Institute
The European Telecommunications Standards Institute is an independent, non-profit, standardization organization in the telecommunications industry in Europe, with worldwide projection...
(ETSI) in response to the earlier CDPD and i-mode
I-mode
NTT DoCoMo's i-mode is a mobile internet service popular in Japan. Unlike Wireless Application Protocol, i-mode encompasses a wider variety of internet standards, including web access, e-mail and the packet-switched network that delivers the data...
packet-switched cellular technologies. It is now maintained by the 3rd Generation Partnership Project (3GPP).
GPRS usage charging is based on volume of data, either as part of a bundle or on a pay-as-you-use basis. An example of a bundle is up to 5 GB per month for a fixed fee. Usage above the bundle cap is either charged for per megabyte or disallowed. The pay as you use charging is typically per megabyte of traffic. This contrasts with circuit switching
Circuit switching
Circuit switching is a methodology of implementing a telecommunications network in which two network nodes establish a dedicated communications channel through the network before the nodes may communicate. The circuit guarantees the full bandwidth of the channel and remains connected for the...
data, which is typically billed per minute of connection time, regardless of whether or not the user transfers data during that period.
GPRS is a best-effort service, implying variable throughput
Throughput
In communication networks, such as Ethernet or packet radio, throughput or network throughput is the average rate of successful message delivery over a communication channel. This data may be delivered over a physical or logical link, or pass through a certain network node...
and latency
Latency
Latency or latent may refer to:*Latency period , the time between exposure to a pathogen, chemical or radiation, and when symptoms first become apparent...
that depend on the number of other users sharing the service concurrently, as opposed to circuit switching
Circuit switching
Circuit switching is a methodology of implementing a telecommunications network in which two network nodes establish a dedicated communications channel through the network before the nodes may communicate. The circuit guarantees the full bandwidth of the channel and remains connected for the...
, where a certain quality of service
Quality of service
The quality of service refers to several related aspects of telephony and computer networks that allow the transport of traffic with special requirements...
(QoS) is guaranteed during the connection. In 2G systems, GPRS provides data rates of 56-114 kbit/second. 2G
2G
2G is short for second-generation wireless telephone technology. Second generation 2G cellular telecom networks were commercially launched on the GSM standard in Finland by Radiolinja in 1991...
cellular technology combined with GPRS is sometimes described as 2.5G, that is, a technology between the second (2G
2G
2G is short for second-generation wireless telephone technology. Second generation 2G cellular telecom networks were commercially launched on the GSM standard in Finland by Radiolinja in 1991...
) and third (3G
3G
3G or 3rd generation mobile telecommunications is a generation of standards for mobile phones and mobile telecommunication services fulfilling the International Mobile Telecommunications-2000 specifications by the International Telecommunication Union...
) generations of mobile telephony. It provides moderate-speed data transfer, by using unused time division multiple access
Time division multiple access
Time division multiple access is a channel access method for shared medium networks. It allows several users to share the same frequency channel by dividing the signal into different time slots. The users transmit in rapid succession, one after the other, each using its own time slot. This...
(TDMA) channels in, for example, the GSM system. GPRS is integrated into GSM Release 97 and newer releases.
Technical overview
The GPRS core network allows 2G2G
2G is short for second-generation wireless telephone technology. Second generation 2G cellular telecom networks were commercially launched on the GSM standard in Finland by Radiolinja in 1991...
, 3G
3G
3G or 3rd generation mobile telecommunications is a generation of standards for mobile phones and mobile telecommunication services fulfilling the International Mobile Telecommunications-2000 specifications by the International Telecommunication Union...
and WCDMA mobile networks
Mobile telephony
Mobile telephony is the provision of telephone services to phones which may move around freely rather than stay fixed in one location. Mobile phones connect to a terrestrial cellular network of base stations , whereas satellite phones connect to orbiting satellites...
to transmit IP
Internet Protocol
The Internet Protocol is the principal communications protocol used for relaying datagrams across an internetwork using the Internet Protocol Suite...
packets to external networks such as the Internet
Internet
The Internet is a global system of interconnected computer networks that use the standard Internet protocol suite to serve billions of users worldwide...
. The GPRS system is an integrated part of the GSM network switching subsystem
Network Switching Subsystem
Network switching subsystem is the component of a GSM system that carries out call switching and mobility management functions for mobile phones roaming on the network of base stations...
.
Services offered
GPRS extends the GSM Packet circuit switched data capabilities and makes the following services possible:- SMS messaging and broadcasting
- "Always on" internet access
- Multimedia messaging serviceMultimedia Messaging ServiceMultimedia Messaging Service, or MMS, is a standard way to send messages that include multimedia content to and from mobile phones. It extends the core SMS capability that allowed exchange of text messages only up to 160 characters in length.The most popular use is to send photographs from...
(MMS) - Push to talkPush to talkPush-to-talk , also known as Press-to-Transmit, is a method of conversing on half-duplex communication lines, including two-way radio, using a momentary button to switch from voice reception mode to transmit mode....
over cellular (PoC) - Instant messagingInstant messagingInstant Messaging is a form of real-time direct text-based chatting communication in push mode between two or more people using personal computers or other devices, along with shared clients. The user's text is conveyed over a network, such as the Internet...
and presence—wireless villageWireless VillageWireless Village is a set of specifications for mobile instant messaging and presence services. It is intended to be a standard for cellphones and mobile devices to use these services across platforms.... - Internet applications for smart devices through wireless application protocolWireless Application ProtocolWireless Application Protocol is a technical standard for accessing information over a mobile wireless network.A WAP browser is a web browser for mobile devices such as mobile phones that uses the protocol.Before the introduction of WAP, mobile service providers had limited opportunities to offer...
(WAP) - Point-to-point (P2P) service: inter-networking with the Internet (IP)
- Point-to-MultipointPoint-to-multipointPoint-to-multipoint communication is a term that is used in the telecommunications field which refers to communication which is accomplished via a specific and distinct type of one-to-many connection, providing multiple paths from a single location to multiple locations.Point-to-multipoint is often...
(P2M) service: point-to-multipoint multicast and point-to-multipoint group calls
If SMS over GPRS is used, an SMS transmission speed of about 30 SMS messages per minute may be achieved. This is much faster than using the ordinary SMS over GSM, whose SMS transmission speed is about 6 to 10 SMS messages per minute.
Protocols supported
GPRS supports the following protocols:- Internet protocolInternet ProtocolThe Internet Protocol is the principal communications protocol used for relaying datagrams across an internetwork using the Internet Protocol Suite...
(IP). In practice, built-in mobile browsers use IPv4IPv4Internet Protocol version 4 is the fourth revision in the development of the Internet Protocol and the first version of the protocol to be widely deployed. Together with IPv6, it is at the core of standards-based internetworking methods of the Internet...
since IPv6IPv6Internet Protocol version 6 is a version of the Internet Protocol . It is designed to succeed the Internet Protocol version 4...
was not yet popular. - Point-to-point protocolPoint-to-Point ProtocolIn networking, the Point-to-Point Protocol is a data link protocol commonly used in establishing a direct connection between two networking nodes...
(PPP). In this mode PPP is often not supported by the mobile phone operator but if the mobile is used as a modem to the connected computer, PPP is used to tunnel IP to the phone. This allows an IP address to be assigned dynamically to the mobile equipment. - X.25X.25X.25 is an ITU-T standard protocol suite for packet switched wide area network communication. An X.25 WAN consists of packet-switching exchange nodes as the networking hardware, and leased lines, Plain old telephone service connections or ISDN connections as physical links...
connections. This is typically used for applications like wireless payment terminals, although it has been removed from the standard. X.25 can still be supported over PPP, or even over IP, but doing this requires either a network based router to perform encapsulation or intelligence built in to the end-device/terminal; e.g., user equipment (UE).
When TCP/IP
Internet protocol suite
The Internet protocol suite is the set of communications protocols used for the Internet and other similar networks. It is commonly known as TCP/IP from its most important protocols: Transmission Control Protocol and Internet Protocol , which were the first networking protocols defined in this...
is used, each phone can have one or more IP address
IP address
An Internet Protocol address is a numerical label assigned to each device participating in a computer network that uses the Internet Protocol for communication. An IP address serves two principal functions: host or network interface identification and location addressing...
es allocated. GPRS will store and forward the IP packets to the phone even during handover
Handover
In cellular telecommunications, the term handover or handoff refers to the process of transferring an ongoing call or data session from one channel connected to the core network to another...
. The TCP handles any packet loss (e.g. due to a radio noise induced pause).
Hardware
Devices supporting GPRS are divided into three classes:Class A: Can be connected to GPRS service and GSM service (voice, SMS), using both at the same time. Such devices are known to be available today.
Class B: Can be connected to GPRS service and GSM service (voice, SMS), but using only one or the other at a given time. During GSM service (voice call or SMS), GPRS service is suspended, and then resumed automatically after the GSM service (voice call or SMS) has concluded. Most GPRS mobile devices are Class B.
Class C: Are connected to either GPRS service or GSM service (voice, SMS). Must be switched manually between one or the other service.
A true Class A device may be required to transmit on two different frequencies at the same time, and thus will need two radios. To get around this expensive requirement, a GPRS mobile may implement the dual transfer mode (DTM)
Dual Transfer Mode
Dual Transfer Mode is a protocol based on the GSM standard that allows simultaneous transfer of Circuit switched voice and Packet switched data over the same radio channel . DTM is a 3GPP baseline R99 feature....
feature. A DTM-capable mobile may use simultaneous voice and packet data, with the network coordinating to ensure that it is not required to transmit on two different frequencies at the same time. Such mobiles are considered pseudo-Class A, sometimes referred to as "simple class A". Some networks support DTM since 2007.
Antenna (radio)
An antenna is an electrical device which converts electric currents into radio waves, and vice versa. It is usually used with a radio transmitter or radio receiver...
. Modems can be added as cards (for laptops) or external USB devices which are similar in shape and size to a computer mouse, or nowadays more like a pendrive.
Addressing
A GPRS connection is established by reference to its access point nameAccess Point Name
Access Point Name is a computer protocol that typically allows a user's computer to access the Internet using the mobile phone network.On a technical level it is a configurable network identifier used by a mobile device when connecting to a GSM carrier...
(APN). The APN defines the services such as wireless application protocol
Wireless Application Protocol
Wireless Application Protocol is a technical standard for accessing information over a mobile wireless network.A WAP browser is a web browser for mobile devices such as mobile phones that uses the protocol.Before the introduction of WAP, mobile service providers had limited opportunities to offer...
(WAP) access, short message service
Short message service
Short Message Service is a text messaging service component of phone, web, or mobile communication systems, using standardized communications protocols that allow the exchange of short text messages between fixed line or mobile phone devices...
(SMS), multimedia messaging service
Multimedia Messaging Service
Multimedia Messaging Service, or MMS, is a standard way to send messages that include multimedia content to and from mobile phones. It extends the core SMS capability that allowed exchange of text messages only up to 160 characters in length.The most popular use is to send photographs from...
(MMS), and for Internet
Internet
The Internet is a global system of interconnected computer networks that use the standard Internet protocol suite to serve billions of users worldwide...
communication services such as email
Email
Electronic mail, commonly known as email or e-mail, is a method of exchanging digital messages from an author to one or more recipients. Modern email operates across the Internet or other computer networks. Some early email systems required that the author and the recipient both be online at the...
and World Wide Web
World Wide Web
The World Wide Web is a system of interlinked hypertext documents accessed via the Internet...
access.
In order to set up a GPRS connection for a wireless modem
Wireless modem
A wireless modem is a type of modulator-demodulator which connects to a wireless network instead of using telephone or cable television lines...
, a user must specify an APN, optionally a user name and password, and very rarely an IP address
IP address
An Internet Protocol address is a numerical label assigned to each device participating in a computer network that uses the Internet Protocol for communication. An IP address serves two principal functions: host or network interface identification and location addressing...
, all provided by the network operator.
Coding schemes and speeds
The upload and download speeds that can be achieved in GPRS depend on a number of factors such as:- the number of BTSBase Transceiver StationA base transceiver station or cell site is a piece of equipment that facilitates wireless communication between user equipment and a network. UEs are devices like mobile phones , WLL phones, computers with wireless internet connectivity, WiFi and WiMAX gadgets etc...
TDMA time slots assigned by the operator - the channel encoding used.
- the maximum capability of the mobile device expressed as a GPRS multislot class
Multiple access schemes
The multiple access methods used in GSM with GPRS are based on frequency division duplex (FDD) and TDMA. During a session, a user is assigned to one pair of up-link and down-link frequency channels. This is combined with time domain statistical multiplexingStatistical multiplexing
Statistical multiplexing is a type of communication link sharing, very similar to dynamic bandwidth allocation . In statistical multiplexing, a communication channel is divided into an arbitrary number of variable bit-rate digital channels or data streams. The link sharing is adapted to the...
; i.e., packet mode communication, which makes it possible for several users to share the same frequency channel. The packets have constant length, corresponding to a GSM time slot. The down-link uses first-come first-served packet scheduling, while the up-link uses a scheme very similar to reservation ALOHA
Reservation ALOHA
Reservation ALOHA, or R-ALOHA, is a channel access method for wireless transmission that allows uncoordinated users to share a common transmission resource. Reservation ALOHA is a schema or rule set for the division of transmission resources over fixed time increments, also known as slots...
(R-ALOHA). This means that slotted ALOHA (S-ALOHA) is used for reservation inquiries during a contention phase, and then the actual data is transferred using dynamic TDMA with first-come first-served scheduling.
Channel encoding
Channel encoding is based on a convolutional codeConvolutional code
In telecommunication, a convolutional code is a type of error-correcting code in which* each m-bit information symbol to be encoded is transformed into an n-bit symbol, where m/n is the code rate and...
at different code rate
Code rate
In telecommunication and information theory, the code rate of a forward error correction code is the proportion of the data-stream that is useful...
s and GMSK modulation defined for GSM. The following table summarises the options:
| Coding scheme |
Speed (kbit/s) |
|---|---|
| CS-1 | 8.0 |
| CS-2 | 12.0 |
| CS-3 | 14.4 |
| CS-4 | 20.0 |
The least robust, but fastest, coding scheme (CS-4) is available near a base transceiver station
Base Transceiver Station
A base transceiver station or cell site is a piece of equipment that facilitates wireless communication between user equipment and a network. UEs are devices like mobile phones , WLL phones, computers with wireless internet connectivity, WiFi and WiMAX gadgets etc...
(BTS), while the most robust coding scheme (CS-1) is used when the mobile station (MS) is further away from a BTS.
Using the CS-4 it is possible to achieve a user speed of 20.0 kbit/s per time slot. However, using this scheme the cell coverage is 25% of normal. CS-1 can achieve a user speed of only 8.0 kbit/s per time slot, but has 98% of normal coverage. Newer network equipment can adapt the transfer speed automatically depending on the mobile location.
In addition to GPRS, there are two other GSM technologies which deliver data services: circuit-switched data
Circuit Switched Data
Circuit Switched Data is the original form of data transmission developed for the time division multiple access -based mobile phone systems like Global System for Mobile Communications...
(CSD) and high-speed circuit-switched data
High-Speed Circuit-Switched Data
High-speed circuit-switched data , is an enhancement to Circuit Switched Data , the original data transmission mechanism of the GSM mobile phone system, four times faster than GSM, with data rates up to 38.4 kbit/s....
(HSCSD). In contrast to the shared nature of GPRS, these instead establish a dedicated circuit (usually billed per minute). Some applications such as video calling may prefer HSCSD, especially when there is a continuous flow of data between the endpoints.
The following table summarises some possible configurations of GPRS and circuit switched data services.
| Technology | Download (kbit/s) | Upload (kbit/s) | TDMA Timeslots allocated |
|---|---|---|---|
| CSD | 9.6 | 9.6 | 1+1 |
| HSCSD | 28.8 | 14.4 | 2+1 |
| HSCSD | 43.2 | 14.4 | 3+1 |
| GPRS | 80.0 | 20.0 (Class 8 & 10 and CS-4) | 4+1 |
| GPRS | 60.0 | 40.0 (Class 10 and CS-4) | 3+2 |
| EGPRS (EDGE) | 236.8 | 59.2 (Class 8, 10 and MCS-9) | 4+1 |
| EGPRS (EDGE) | 177.6 | 118.4 (Class 10 and MCS-9) | 3+2 |
Multislot Class
The multislot class determines the speed of data transfer available in the UplinkUplink
A telecommunications link is generally one of several types of information transmission paths such as those provided by communication satellites to connect two points on earth.-Uplink:...
and Downlink directions. It is a value between 1 to 45 which the network uses to allocate radio channels in the uplink and downlink direction. Multislot class with values greater than 31 are referred to as high multislot classes.
A multislot allocation is represented as, for example, 5+2. The first number is the number of downlink timeslots and the second is the number of uplink timeslots allocated for use by the mobile station. A commonly used value is class 10 for many GPRS/EGPRS mobiles which uses a maximum of 4 timeslots in downlink direction and 2 timeslots in uplink direction. However simultaneously a maximum number of 5 simultaneous timeslots can be used in both uplink and downlink. The network will automatically configure the for either 3+2 or 4+1 operation depending on the nature of data transfer.
Some high end mobiles, usually also supporting UMTS also support GPRS/EDGE
Edge
- Aviation :* Leading edge, a line connecting the forward-most points of a wing's profile* Trailing edge, the rear edge of the wing* Zivko Edge 540, an aerobatic aircraft- Mathematics, science and technology :...
multislot class 32. According to 3GPP
3GPP
The 3rd Generation Partnership Project is a collaboration between groups of telecommunications associations, known as the Organizational Partners...
TS 45.002 (Release 6), Table B.2, mobile stations of this class support 5 timeslots in downlink and 3 timeslots in uplink with a maximum number of 6 simultaneously used timeslots. If data traffic is concentrated in downlink direction the network will configure the connection for 5+1 operation. When more data is transferred in the uplink the network can at any time change the constellation to 4+2 or 3+3. Under the best reception conditions, i.e. when the best EDGE modulation and coding scheme can be used, 5 timeslots can carry a bandwidth of 5*59.2 kbit/s = 296 kbit/s. In uplink direction, 3 timeslots can carry a bandwidth of 3*59.2 kbit/s = 177.6 kbit/s.
Multislot Classes for GPRS/EGPRS
| Multislot Class | Downlink TS | Uplink TS | Active TS |
|---|---|---|---|
| 1 | 1 | 1 | 2 |
| 2 | 2 | 1 | 3 |
| 3 | 2 | 2 | 3 |
| 4 | 3 | 1 | 4 |
| 5 | 2 | 2 | 4 |
| 6 | 3 | 2 | 4 |
| 7 | 3 | 3 | 4 |
| 8 | 4 | 1 | 5 |
| 9 | 3 | 2 | 5 |
| 10 | 4 | 2 | 5 |
| 11 | 4 | 3 | 5 |
| 12 | 4 | 4 | 5 |
| 30 | 5 | 1 | 6 |
| 31 | 5 | 2 | 6 |
| 32 | 5 | 3 | 6 |
| 33 | 5 | 4 | 6 |
| 34 | 5 | 5 | 6 |
Attributes of a multislot class
Each multislot class identifies the following:- the maximum number of Timeslots that can be allocated on uplink
- the maximum number of Timeslots that can be allocated on downlink
- the total number of timeslots which can be allocated by the network to the mobile
- the time needed for the MS to perform adjacent cell signal level measurement and get ready to transmit
- the time needed for the MS to get ready to transmit
- the time needed for the MS to perform adjacent cell signal level measurement and get ready to receive
- the time needed for the MS to get ready to receive.
The different multislot class specification is detailed in the Annex B of the 3GPP Technical Specification 45.002 (Multiplexing and multiple access on the radio path)
Usability
The maximum speed of a GPRS connection offered in 2003 was similar to a modemModem
A modem is a device that modulates an analog carrier signal to encode digital information, and also demodulates such a carrier signal to decode the transmitted information. The goal is to produce a signal that can be transmitted easily and decoded to reproduce the original digital data...
connection in an analog wire telephone network, about 32-40 kbit/s, depending on the phone used. Latency
Lag
Lag is a common word meaning to fail to keep up or to fall behind. In real-time applications, the term is used when the application fails to respond in a timely fashion to inputs...
is very high; round-trip time (RTT) is typically about 600-700 ms and often reaches 1 s. GPRS is typically prioritized lower than speech, and thus the quality of connection varies greatly.
Devices with latency/RTT improvements (via, for example, the extended UL TBF mode feature) are generally available. Also, network upgrades of features are available with certain operators. With these enhancements the active round-trip time can be reduced, resulting in significant increase in application-level throughput speeds.
See also
- Code division multiple accessCode division multiple accessCode division multiple access is a channel access method used by various radio communication technologies. It should not be confused with the mobile phone standards called cdmaOne, CDMA2000 and WCDMA , which are often referred to as simply CDMA, and use CDMA as an underlying channel access...
(CDMA) - Enhanced data rates for GSM evolutionEnhanced Data Rates for GSM EvolutionEnhanced Data rates for GSM Evolution is a digital mobile phone technology that allows improved data transmission rates as a backward-compatible extension of GSM...
(EDGE) - Universal mobile telephone systemUniversal Mobile Telecommunications SystemUniversal Mobile Telecommunications System is a third generation mobile cellular technology for networks based on the GSM standard. Developed by the 3GPP , UMTS is a component of the International Telecommunications Union IMT-2000 standard set and compares with the CDMA2000 standard set for...
(UMTS) - GPRS core networkGPRS Core NetworkThe GPRS core network is the central part of the General Packet Radio Service which allows 2G, 3G and WCDMA mobile networks to transmit IP packets to external networks such as the Internet...
- Sub-network dependent convergence protocolSNDCPSNDCP stands for Sub Network Dependent Convergence Protocol.This is part of layer 3 of a GPRS protocol specification. SNDCP interfaces to the Internet Protocol at the top, and to the GPRS-specific Logical Link Control protocol at the bottom....
(SNDCP) - IP Multimedia SubsystemIP Multimedia SubsystemThe IP Multimedia Subsystem or IP Multimedia Core Network Subsystem is an architectural framework for delivering Internet Protocol multimedia services. It was originally designed by the wireless standards body 3rd Generation Partnership Project , as a part of the vision for evolving mobile...
- High-speed downlink packet accessHigh-Speed Downlink Packet AccessHigh-Speed Downlink Packet Access is an enhanced 3G mobile telephony communications protocol in the High-Speed Packet Access family, also dubbed 3.5G, 3G+ or turbo 3G, which allows networks based on Universal Mobile Telecommunications System to have higher data transfer speeds and capacity...
(HSDPA) - Cellular data communication protocolCellular data communication protocolThe protocols described here are from the Cellular Data Communication Protocol.GSM and CDMA protocols include:*BSMAP Base Station Management Application Part*BSSAP BSS Application Part*BSSLAP*BSSAPLE*BSSMAP BSS Management Application Part...
- List of device bandwidths