GPRS and EDGE are packet-switched mobile data technologies that are part of the most widely deployed second-generation (2G) cellular technology standard, GSM (Global System for Mobile Communications). Before GPRS and EDGE, GSM networks had limited options for providing mobile internet.
GPRS or General Packet Radio Service is a technology that introduced packet-switched mobile internet in GSM networks in 2000. EDGE or Enhanced Data rates for Global Evolution is a technology that enhances GPRS through E-GPRS (Enhanced GPRS) and HDSCD through ECSD (Enhanced Circuit-Switched Data).
When GSM networks were initially introduced in 1991, they only had the circuit-switched capability that required dedicated timeslots for offering voice and text messaging services. GSM network offered limited mobile data services through the CSD (Circuit-Switched-Data) technology. CSD was later enhanced to HSCSD (High-Speed Circuit Switched Data). GPRS and EDGE were game-changers as they used more efficient technologies to improve the data rates in GSM networks considerably.
GPRS introduced packet-switched mobile data in GSM networks to enable peak data rates of up to 171.2 kbps; EDGE is an update that effectively tripled the peak data rates of GPRS through E-GPRS (Enhanced GPRS) to up to 384 kbps. EDGE also improved the performance of HSCSD through ECSD (Enhanced CSD).
GPRS and EDGE (EGPRS) are two network enhancements made to the GSM networks (Global System for Mobile Communications) as part of the second generation of mobile network evolution. The network evolution later led to technologies like 3G UMTS, 4G LTE and 5G New Radio (NR), but GPRS and EGPRS still exist today (2021). We encounter them when we are in remote geographical areas with limited 3G, 4G or 5G coverage. I have written a dedicated post on the E symbol on your phone, which represents the EDGE technology.
Circuit-Switched mobile data in 2G GSM: CSD, HSCSD and ECSD
2G GSM networks initially employed circuit-switched mobile data technology, CSD (Circuit-Switched-Data), to offer a peak data rate of up to 9.6 kbps; CSD was enhanced through HSCSD (High-Speed Circuit-Switched Data) and ECSD (Enhanced Circuit-Switched Data) to offer peak data rates of up to 64 kbps.
In GSM, each transceiver (radio unit) is assigned one frequency channel (ARFCN) that creates one cell. Each cell has eight (8) timeslots to accommodate multiple calls or text messages. The original GSM networks employed a technology called CSD (Circuit-Switched-Data) that was able to utilise timeslots of the radio units for providing mobile data. CSD allowed a maximum download speed of up to 9.6 kbps by using a single timeslot. High-Speed Circuit Switched Data (HSCSD) was an enhancement that could improve the data speeds of CSD by up to 6 times. HSCSD used better error-coding techniques to increase the maximum data rate of a single time slot from 9.6 kbps to 14.4 kbps. HSCSD could offer a maximum data rate of up to 64 kbps by using multiple timeslots in the GSM network, requiring upgrades to the mobile phones. Later, as part of the EDGE enhancement, ECSD (Enhanced Circuit Switched Data) improved the data rate per timeslot in HSCSD. However, the maximum data rate per mobile device still remained at 64 kbps. ECSD allowed mobile operators to use the eight (8) timeslots of a frequency channel more efficiently because, with ECSD, they were able to use fewer timeslots per mobile device.
GPRS introduced packet-switched mobile data in GSM
GPRS stands for General Packet Radio Service, which introduced packet-switched mobile data in 2G GSM networks in 2000 before the launch of 3G. GPRS required two additional nodes, SGSN and GGSN, in the GSM core network to enable peak data rates of 171.2 kbps through efficient use of shared timeslots.
While HSCSD was an easy solution for mobile operators, it was not very efficient because it needed a mobile phone to stay connected to the network for the entire data session, even when the user was not downloading or uploading). Therefore, mobile operators needed a different solution that came in the form of GPRS based on the packet-switched technology. GPRS – General Packet Radio Service was a step-change for the GSM networks as it introduced a new packet-switched part to the existing network architecture. In the packet-switched technique, mobile data is sent and received in packets of data bursts at different time intervals by sharing the available capacity with multiple users. So rather than dedicating the full capacity to one session, the capacity is shared between multiple users to facilitate multiple sessions. In this way, when a certain user in a certain session is not sending/receiving any data bursts, other users in other sessions can utilise the same capacity. GPRS could enable up to 171.2 kbps in the downlink through packet-switched technology for downloads. Like HSCSD, GPRS also made use of multiple timeslots, but it was more efficient as it could offer a higher bit rate per timeslot, and more importantly, it did not require engaging the network resources permanently for the whole duration of the data sessions.
EDGE uses E-GPRS to improve GPRS and ECSD to enhance HSCSD
EDGE stands for Enhanced Data rates for Global Evolution, and it is a pre-3G technology that employs advanced modulation techniques to effectively triple the performance of packet-switched GPRS through E-GPRS (Enhanced GPRS) and circuit-switched HSCSD through ECSD (Enhanced CSD).
EGPRS stands for Enhanced General Packet Radio Service, and it is the enhancement added to the GPRS networks as part of Enhanced Data rates for Global Evolution – EDGE. EDGE, which is also often referred to as 2.75G, is a network enhancement introduced to improve the achievable data rates from GPRS and HSCSD. However, the most notable part of EDGE is EGPRS because it was applied to the packet-switched GPRS technology as a critical step in the evolution of mobile data. While GPRS networks could already offer up to 171.2 kbps, EGPRS used a superior modulation scheme, 8-PSK (Octagonal Phase Shift Keying), to nearly triple the data rates that GPRS could initially offer.
Using all eight (8) timeslots, EGPRS (Enhanced General Packet Radio Service) can theoretically enable peak data rates of 473 kbps; however, in practice, the known peak speed of EGPRS is 384 kbps. While 384 kbps can support basic mobile internet tasks, we don’t generally get peak speeds in real life.
Generally, depending on how many people are on the network and how far you are from the base station, you may get an average data rate of around 130 to 200 kbps for downloads. EGPRS also uses the packet-switched methodology to send and receive mobile data just like GPRS. The capacity available on the packet-switched part of the network is shared between multiple users. The packets of data bursts are sent at different intervals for different users, making the overall process much more efficient. GPRS and EDGE are often referred to as 2.5G and 2.75G, respectively. Have a look at our dedicated post on the data speeds with GPRS, EDGE and other packet-switched networks.
Here are some helpful downloads
Thank you for reading this post. I hope it helped you in developing a better understanding of cellular networks. Sometimes, we need extra support, especially when preparing for a new job, studying a new topic, or buying a new phone. Whatever you are trying to do, here are some downloads that can help you:
Students & fresh graduates: If you are just starting, the complexity of the cellular industry can be a bit overwhelming. But don’t worry, I have created this FREE ebook so you can familiarise yourself with the basics like 3G, 4G etc. As a next step, check out the latest edition of the same ebook with more details on 4G & 5G networks with diagrams. You can then read Mobile Networks Made Easy, which explains the network nodes, e.g., BTS, MSC, GGSN etc.
Professionals: If you are an experienced professional but new to mobile communications, it may seem hard to compete with someone who has a decade of experience in the cellular industry. But not everyone who works in this industry is always up to date on the bigger picture and the challenges considering how quickly the industry evolves. The bigger picture comes from experience, which is why I’ve carefully put together a few slides to get you started in no time. So if you work in sales, marketing, product, project or any other area of business where you need a high-level view, Introduction to Mobile Communications can give you a quick start. Also, here are some templates to help you prepare your own slides on the product overview and product roadmap.
