General Packet Radio Service

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General Packet Radio Service (GPRS), also called 2.5G, [lower-alpha 1] is a mobile data standard on the 2G cellular communication network's global system for mobile communications (GSM). [1] Networks and mobile devices with GPRS started to roll out around the year 2001. [2] At the time of introduction it offered for the first time [lower-alpha 2] seamless mobile data transmission using packet data for an "always-on" connection (eliminating the need to "dial-up"), [3] providing improved Internet access for web, email, WAP services, and Multimedia Messaging Service (MMS). [4]

Contents

GPRS provides theoretical data rates of 56–114  kbit/s - [5] faster than the older CSD - and uses unused time-division multiple access (TDMA) channels in the GSM system for efficiency. 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. Unlike older circuit switching data, GPRS was sold according to the total volume of data transferred instead of time spent online, [6] which is now standard. GPRS was succeeded by EDGE (2.75G) which provided improved performance.

Sony Ericsson K310a showing Wikipedia's homepage via internet using a GPRS connection SonyEricssonK310-GPRS-Wikipedia.jpg
Sony Ericsson K310a showing Wikipedia's homepage via internet using a GPRS connection

GPRS was established by European Telecommunications Standards Institute (ETSI) in response to the earlier CDPD and i-mode packet-switched cellular technologies and is integrated into GSM Release 97 and newer releases. It is now maintained by the 3rd Generation Partnership Project (3GPP). [7] [8]

Technical overview

The GPRS core network allows 2G, 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. [9] [10] [11]

Services offered

GPRS extends the GSM Packet circuit switched data capabilities and makes the following services possible:

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.

Frequencies

As the GPRS standard is an extension of GSM capabilities, the service operates on the 2G and 3G cellular communication GSM frequencies. [10] [12] GPRS devices can typically use (one or more) of the frequencies within one of the frequency bands the radio supports (850, 900, 1800, 1900 MHz). Depending on the device, location and intended use, regulations may be imposed either restricting or explicitly specifying authorised frequency bands. [12] [13] [14]

GSM-850 and GSM-1900 are used in the United States, Canada, and many other countries in the Americas. GSM-900 and GSM-1800 are used in: Europe, Middle East, Africa and most of Asia. In South Americas these bands are used in Costa Rica (GSM-1800), Brazil (GSM-850, 900 and 1800), Guatemala (GSM-850, GSM-900 and 1900), El Salvador (GSM-850, GSM-900 and 1900). There is a more comprehensive record of international cellular service frequency assignments

Protocols supported

GPRS supports the following protocols:

When TCP/IP is used, each phone can have one or more IP addresses allocated. GPRS will store and forward the IP packets to the phone even during handover. The TCP restores any packets lost (e.g. due to a radio noise induced pause).

Hardware

Devices supporting GPRS are grouped into three classes:

Class A
Can be connected to GPRS service and GSM service (voice, SMS) simultaneously. Such devices are now available[ as of? ].
Class B
Can be connected to GPRS service and GSM service (voice, SMS), but using only one at a time. During GSM service (voice call or SMS), GPRS service is suspended and 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) and must be switched manually between one service and the other.

Because a Class A device must service GPRS and GSM networks together, it effectively needs two radios. To avoid this hardware requirement, a GPRS mobile device may implement the dual transfer mode (DTM) feature. A DTM-capable mobile can handle both GSM packets and GPRS packets with network coordination to ensure both types are not transmitted at the same time. Such devices are considered pseudo-Class A, sometimes referred to as "simple class A". Some networks have supported DTM since 2007[ citation needed ].

Huawei E220 3G/GPRS Modem Huawei E220 (Three).jpg
Huawei E220 3G/GPRS Modem

USB 3G/GPRS modems have a terminal-like interface over USB with V.42bis, and RFC   1144 data formats. Some models include an external antenna connector. Modem cards for laptop PCs, or external USB modems are available, similar in shape and size to a computer mouse, or a pendrive.

Addressing

A GPRS connection is established by reference to its access point name (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, provided by the network operator.

GPRS modems and modules

GSM module or GPRS modules are similar to modems, but there's one difference: the modem is an external piece of equipment, whereas the GSM module or GPRS module can be integrated within an electrical or electronic equipment. It is an embedded piece of hardware. A GSM mobile, on the other hand, is a complete embedded system in itself. It comes with embedded processors dedicated to provide a functional interface between the user and the mobile network.

Coding schemes and speeds

The upload and download speeds that can be achieved in GPRS depend on a number of factors such as:

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 multiplexing 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.

Channel encoding

The channel encoding process in GPRS consists of two steps: first, a cyclic code is used to add parity bits, which are also referred to as the Block Check Sequence, followed by coding with a possibly punctured convolutional code. [15] The Coding Schemes CS-1 to CS-4 specify the number of parity bits generated by the cyclic code and the puncturing rate of the convolutional code. [15] In Coding Schemes CS-1 through CS-3, the convolutional code is of rate 1/2, i.e. each input bit is converted into two coded bits. [15] In Coding Schemes CS-2 and CS-3, the output of the convolutional code is punctured to achieve the desired code rate. [15] In Coding Scheme CS-4, no convolutional coding is applied. [15] The following table summarises the options.

GPRS
Coding scheme		Bitrate including RLC/MAC overhead [lower-alpha 3] [lower-alpha 4]
(kbit/s/slot)		Bitrate excluding RLC/MAC overhead [lower-alpha 5]
(kbit/s/slot)		 Modulation Code rate
CS-19.208.00GMSK1/2
CS-213.5512.00GMSK≈2/3
CS-315.7514.40GMSK≈3/4
CS-421.5520.00GMSK1
  1. ↑ 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.
  2. ↑ First time on GSM networks
  3. ↑ This is rate at which the RLC/MAC layer protocol data unit (PDU) (called a radio block) is transmitted. As shown in TS 44.060 section 10.0a.1, [16] a radio block consists of MAC header, RLC header, RLC data unit and spare bits. The RLC data unit represents the payload, the rest is overhead. The radio block is coded by the convolutional code specified for a particular Coding Scheme, which yields the same PHY layer data rate for all Coding Schemes.
  4. ↑ Cited in various sources, e.g. in TS 45.001 table 1. [15] is the bitrate including the RLC/MAC headers, but excluding the uplink state flag (USF), which is part of the MAC header, [17] yielding a bitrate that is 0.15 kbit/s lower.
  5. ↑ The net bitrate here is the rate at which the RLC/MAC layer payload (the RLC data unit) is transmitted. As such, this bit rate excludes the header overhead from the RLC/MAC layers.

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.

TechnologyDownload (kbit/s)Upload (kbit/s)TDMA timeslots allocated (DL+UL)
CSD9.69.61+1
HSCSD28.814.42+1
HSCSD43.214.43+1
GPRS85.621.4 (Class 8 & 10 and CS-4)4+1
GPRS64.242.8 (Class 10 and CS-4)3+2
EGPRS (EDGE)236.859.2 (Class 8, 10 and MCS-9)4+1
EGPRS (EDGE)177.6118.4 (Class 10 and MCS-9)3+2

Multislot Class

The multislot class determines the speed of data transfer available in the Uplink and Downlink directions. It is a value between 1 and 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 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 12), Table B.1, [18] 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. [19]

Multislot Classes for GPRS/EGPRS

Multislot ClassDownlink TSUplink TSActive TS
1112
2213
3223
4314
5224
6324
7334
8415
9325
10425
11435
12445
30516
31526
32536
33546
34556

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 modem 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 1s. 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.

History

GSM was designed for voice, not data. It did not provide direct access to the Internet and it had a limited capacity of 9600 bauds per second. [20] The limitations of Circuit Switched Data (CSD) also included higher costs. GPRS opened in 2000 [21] as a packet-switched data service embedded in the channel-switched cellular radio network GSM. GPRS extends the reach of the fixed Internet by connecting mobile terminals worldwide.

The CELLPAC [22] protocol developed 1991–1993 was the trigger point for starting in 1993 the specification of standard GPRS by ETSI SMG. Especially, the CELLPAC Voice & Data functions introduced in a 1993 ETSI Workshop contribution [23] anticipate what was later known to be the roots of GPRS. This workshop contribution is referenced in 22 GPRS-related US patents. [24] Successor systems to GSM/GPRS like W-CDMA (UMTS) and LTE rely on key GPRS functions for mobile Internet access as introduced by CELLPAC.

According to a study on history of GPRS development, [25] Bernhard Walke and his student Peter Decker are the inventors of GPRS — the first system providing worldwide mobile Internet access.

Enhanced GPRS

This section is an excerpt from Enhanced Data rates for GSM Evolution.[ edit ]
EDGE sign shown in notification bar on an Android-based smartphone EDGE symbol Android.png
EDGE sign shown in notification bar on an Android-based smartphone

Enhanced Data rates for GSM Evolution (EDGE), also known as 2.75G, Enhanced GPRS (EGPRS), IMT Single Carrier (IMT-SC), and Enhanced Data rates for Global Evolution, is a 2G digital mobile phone technology for data transmission. It is a subset of General Packet Radio Service (GPRS) on the GSM network and improves upon it offering speeds close to 3G technology, hence the name 2.75G. It is also recognized as part of the International Mobile Telecommunications - 2000 (IMT-2000) standard.

EDGE was deployed on GSM networks beginning in 2003 – initially by Cingular (now AT&T) in the United States. [26] Through the introduction of sophisticated methods of coding and transmitting data, EDGE delivers higher bit-rates per radio channel, resulting in a threefold increase in capacity and performance compared with an ordinary GSM/GPRS connection - originally a max speed of 384 kbit/s. [27] EDGE can be used for any packet switched application, such as an Internet connection.

EDGE is standardized also by 3GPP as part of the GSM family. A variant, so called Compact-EDGE, was developed for use in a portion of Digital AMPS network spectrum. [28] EDGE is part of ITU's 3G definition. [29] Evolved EDGE continues in release 7 of the 3GPP standard providing reduced latency and more than doubled performance e.g. to complement High-Speed Packet Access (HSPA). Peak bit-rates of up to 1 Mbit/s and typical bit-rates of 400 kbit/s can be expected.

See also

Related Research Articles

<span class="mw-page-title-main">Enhanced Data rates for GSM Evolution</span> Digital mobile phone technology

Enhanced Data rates for GSM Evolution (EDGE), also known as 2.75G, Enhanced GPRS (EGPRS), IMT Single Carrier (IMT-SC), and Enhanced Data rates for Global Evolution, is a 2G digital mobile phone technology for data transmission. It is a subset of General Packet Radio Service (GPRS) on the GSM network and improves upon it offering speeds close to 3G technology, hence the name 2.75G. It is also recognized as part of the International Mobile Telecommunications - 2000 (IMT-2000) standard.

<span class="mw-page-title-main">GSM</span> Cellular telephone network standard

The Global System for Mobile Communications (GSM) is a standard developed by the European Telecommunications Standards Institute (ETSI) to describe the protocols for second-generation (2G) digital cellular networks used by mobile devices such as mobile phones and tablets. GSM is also a trade mark owned by the GSM Association. "GSM" may also refer to the voice codec initially used in GSM.

The Universal Mobile Telecommunications System (UMTS) is a 3G mobile cellular system for networks based on the GSM standard. Developed and maintained by the 3GPP, UMTS is a component of the International Telecommunication Union IMT-2000 standard set and compares with the CDMA2000 standard set for networks based on the competing cdmaOne technology. UMTS uses wideband code-division multiple access (W-CDMA) radio access technology to offer greater spectral efficiency and bandwidth to mobile network operators.

Personal Digital Cellular (PDC) was a 2G mobile telecommunications standard used exclusively in Japan.

The GPRS core network is the central part of the general packet radio service (GPRS) which allows 2G, 3G and WCDMA mobile networks to transmit Internet Protocol (IP) packets to external networks such as the Internet. The GPRS system is an integrated part of the GSM network switching subsystem.

Mobility management is one of the major functions of a GSM or a UMTS network that allows mobile phones to work. The aim of mobility management is to track where the subscribers are, allowing calls, SMS and other mobile phone services to be delivered to them.

Network switching subsystem (NSS) is the component of a GSM system that carries out call out and mobility management functions for mobile phones roaming on the network of base stations. It is owned and deployed by mobile phone operators and allows mobile devices to communicate with each other and telephones in the wider public switched telephone network (PSTN). The architecture contains specific features and functions which are needed because the phones are not fixed in one location.

<span class="mw-page-title-main">Base station subsystem</span> Section of cellular telephone network

The base station subsystem (BSS) is the section of a traditional cellular telephone network which is responsible for handling traffic and signaling between a mobile phone and the network switching subsystem. The BSS carries out transcoding of speech channels, allocation of radio channels to mobile phones, paging, transmission and reception over the air interface and many other tasks related to the radio network.

In communications, Circuit Switched Data (CSD) is the original form of data transmission developed for the time-division multiple access (TDMA)-based mobile phone systems like Global System for Mobile Communications (GSM). After 2010 many telecommunication carriers dropped support for CSD, and CSD has been superseded by GPRS and EDGE (E-GPRS).

The IP Multimedia Subsystem or IP Multimedia Core Network Subsystem (IMS) is a standardised architectural framework for delivering IP multimedia services. Historically, mobile phones have provided voice call services over a circuit-switched-style network, rather than strictly over an IP packet-switched network. Various voice over IP technologies are available on smartphones; IMS provides a standard protocol across vendors.

The Mobile Application Part (MAP) is an SS7 protocol that provides an application layer for the various nodes in GSM and UMTS mobile core networks and GPRS core networks to communicate with each other in order to provide services to users. The Mobile Application Part is the application-layer protocol used to access the Home Location Register, Visitor Location Register, Mobile Switching Center, Equipment Identity Register, Authentication Centre, Short message service center and Serving GPRS Support Node (SGSN).

<span class="mw-page-title-main">E-UTRA</span> 3GPP interface

E-UTRA is the air interface of 3rd Generation Partnership Project (3GPP) Long Term Evolution (LTE) upgrade path for mobile networks. It is an acronym for Evolved UMTS Terrestrial Radio Access, also known as the Evolved Universal Terrestrial Radio Access in early drafts of the 3GPP LTE specification. E-UTRAN is the combination of E-UTRA, user equipment (UE), and a Node B.

<span class="mw-page-title-main">BSSGP</span>

BSSGP is a protocol used in the GPRS mobile packet data system. It denotes Base Station System GPRS Protocol. It transfers information between two GPRS entities SGSN and BSS over a BSSGP Virtual Connection (BVC). This protocol provides radio-related quality of service and routing information that is required to transmit user data between a BSS and an SGSN. It does not carry out any form of error correction.

<span class="mw-page-title-main">High Speed Packet Access</span> Communications protocols

High Speed Packet Access (HSPA) is an amalgamation of two mobile protocols—High Speed Downlink Packet Access (HSDPA) and High Speed Uplink Packet Access (HSUPA)—that extends and improves the performance of existing 3G mobile telecommunication networks using the WCDMA protocols. A further-improved 3GPP standard called Evolved High Speed Packet Access was released late in 2008, with subsequent worldwide adoption beginning in 2010. The newer standard allows bit rates to reach as high as 337 Mbit/s in the downlink and 34 Mbit/s in the uplink; however, these speeds are rarely achieved in practice.

Dual Transfer Mode (DTM) is a protocol based on the GSM standard that makes simultaneous transfer of Circuit switched (CS) voice and Packet switched (PS) data over the same radio channel (ARFCN) simpler. Without DTM, the mobile device must be capable of reception and transmission simultaneously (full-duplex) requiring complex and expensive circuitry in the mobile terminal. With DTM this requirement doesn't exist and makes the device implementation simpler and cheaper. DTM is a 3GPP feature introduced in R4 of the specification series.

System Architecture Evolution (SAE) is the core network architecture of mobile communications protocol group 3GPP's LTE wireless communication standard.

The Um interface is the air interface for the GSM mobile telephone standard. It is the interface between the mobile station (MS) and the Base transceiver station (BTS). It is called Um because it is the mobile analog to the U interface of ISDN. Um is defined in the GSM 04.xx and 05.xx series of specifications. Um can also support GPRS packet-oriented communication.

<span class="mw-page-title-main">Mobile broadband modem</span> Modem providing Internet access via a wireless connection

A mobile broadband modem, also known as wireless modem or cellular modem, is a type of modem that allows a personal computer or a router to receive wireless Internet access via a mobile broadband connection instead of using telephone or cable television lines. A mobile Internet user can connect using a wireless modem to a wireless Internet Service Provider (ISP) to get Internet access.

In mobile telephony a bearer service is a link between two points, which is defined by a certain set of characteristics. Whenever user equipment (UE) is being provided with any service, the service has to be associated with a Radio Bearer specifying the configuration for layer 2 and physical layer in order to have its QoS clearly defined. Radio bearers are channels offered by Layer 2 to higher layers for the transfer of either user or control data. In other words, Layer 2 offers to the upper layers the service of information transmission between the UE and the UTRAN by means of the Radio Bearers (RBs) and Signaling Radio Bearers (SRBs). Therefore, the service access points between Layer 2 and upper layers are RBs.

References

  1. ↑ "Is General Packet Radio Service (GPRS) 2G, 3G or 4G? – Commsbrief" . Retrieved 2023-07-16.
  2. ↑ "Q&A: GPRS phones". 2001-05-18. Retrieved 2023-07-16.
  3. ↑ "Industry's mobile hopes". 2001-03-23. Retrieved 2024-06-18.
  4. ↑ "Q&A: GPRS phones". 2001-05-18. Retrieved 2024-06-18.
  5. ↑ "General packet radio service from Qkport". Archived from the original on 2010-01-28. Retrieved 2009-12-14.
  6. ↑ "BBC - Bristol - Digital Future - WAP gets a rocket". www.bbc.co.uk. Retrieved 2024-06-18.
  7. ↑ "Welcome to the World of Standards!". ETSI.
  8. ↑ "3GPP – The Mobile Broadband Standard". 3GPP.
  9. ↑ "What Is GPRS (General Packet Radio Service)? Meaning, Working, Advantages, and Applications". Spiceworks. Retrieved 2023-05-01.
  10. 1 2 Sandeep Bhandari (2021-09-17). "Difference Between GSM and GPRS". askanydifference.com. Retrieved 2023-05-01.
  11. ↑ "4G vs GPRS: What is the difference between 4G LTE and GPRS?". Commsbrief. Retrieved 2023-05-01.
  12. 1 2 "Ofcom UK Frequency Allocation (UKFAT) Page". static.ofcom.org.uk. Retrieved 2023-05-01.
  13. ↑ "What frequency does the data traffic use in GPRS?". Honeywell AIDC. Honeywell. 2014-10-07. Archived from the original on 2023-05-01. Retrieved 2023-05-01.
  14. ↑ "Mobile Spectrum Assignments by Country". CellMapper Wiki. Retrieved 2023-05-01.
  15. 1 2 3 4 5 6 3rd Generation Partnership Project (November 2014). "3GGP TS45.001: Technical Specification Group GSM/EDGE Radio Access Network; Physical layer on the radio path; General description". 12.1.0. Retrieved 2015-12-05.{{cite web}}: CS1 maint: numeric names: authors list (link)
  16. ↑ 3rd Generation Partnership Project (June 2015). "3GGP TS45.001: Technical Specification Group GSM/EDGE Radio Access Network; Mobile Station (MS) - Base Station System (BSS) interface; Radio Link Control / Medium Access Control (RLC/MAC) protocol; section 10.0a.1 - GPRS RLC/MAC block for data transfer". 12.5.0. Retrieved 2015-12-05.{{cite web}}: CS1 maint: numeric names: authors list (link)
  17. ↑ 3rd Generation Partnership Project (June 2015). "3GGP TS45.001: Technical Specification Group GSM/EDGE Radio Access Network; Mobile Station (MS) - Base Station System (BSS) interface; Radio Link Control / Medium Access Control (RLC/MAC) protocol; section 10.2.1 - Downlink RLC data block". 12.5.0. Retrieved 2015-12-05.{{cite web}}: CS1 maint: numeric names: authors list (link)
  18. ↑ 3rd Generation Partnership Project (March 2015). "3GGP TS45.002: Technical Specification Group GSM/EDGE Radio Access Network; Multiplexing and multiple access on the radio path (Release 12)". 12.4.0. Retrieved 2015-12-05.{{cite web}}: CS1 maint: numeric names: authors list (link)
  19. ↑ "GPRS and EDGE Multislot Classes". Archived from the original on 2010-11-27. Retrieved 2010-06-21.
  20. ↑ "Tik-111".
  21. ↑ Haynes, John D. (July 2001). Internet Management Issues: A Global Perspective: A Global Perspective. Idea Group Inc (IGI). ISBN   9781591400158.
  22. ↑ Walke, Bernhard H.; Mende, Wolf; Hatziliadis, Georgios (19–22 May 1991). CELLPAC: A Packet Radio Protocol Applied to the Cellular GSM Mobile Radio Network (PDF). Proceedings of 41st IEEE Vehicular Technology Conference. St. Louis, Missouri, USA: IEEE. pp. 408–413. doi:10.1109/VETEC.1991.140520. ISBN   0-87942-582-2. ISSN   1090-3038. Archived (PDF) from the original on 2021-11-17. Retrieved 2021-11-27. (6 pages)
  23. ↑ Decker, Peter; Walke, Bernhard H. (1993-10-13). A General Packet Radio Service proposed for GSM (PDF). ETSI SMG Workshop "GSM in a Future Competitive Environment". Helsinki, Finland. pp. 1–20. Archived (PDF) from the original on 2021-09-18. Retrieved 2021-11-15. (11 pages)
  24. ↑ Program “Publish or Perish”, see returns to a search for P. Decker, B. Walke, their most cited paper that unveils US patents referencing that paper.
  25. ↑ Walke, Bernhard H. (October 2013). "The Roots of GPRS: The First System for Mobile Packet-Based Global Internet Access" (PDF). IEEE Wireless Communications . Aachen, Germany: ComNets Research Group: 12–23. Archived (PDF) from the original on 2021-09-18. Retrieved 2021-11-15. (19 pages)
  26. ↑ http://www.itu.int/ITU-D/imt-2000/MiscDocuments/IMT-Deployments-Rev3.pdf . Retrieved 2008-04-16.{{cite web}}: Missing or empty |title= (help)[ dead link ]
  27. ↑ https://tacs.eu/Analyses/Wireless%20Networks/edge1.pdf
  28. ↑ ETSI SMG2 99/872
  29. ↑ "Archived copy" (PDF). Archived from the original (PDF) on 2009-03-06. Retrieved 2011-05-10.{{cite web}}: CS1 maint: archived copy as title (link)
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