From Circuit Switched to Packet Switch Data: Architecture Evolution and Impact of GPRS and Edge on Mobile Internet

This topic traces the crucial shift in mobile network architecture from inefficient, dedicated circuit-switched data to flexible, shared packet-switched data, highlighting how GPRS and EDGE technologies were pivotal in enabling the mobile internet. GPRS first introduced packet-switched services over the existing GSM network, providing an "always-on" connection for internet access, while EDGE further enhanced these speeds, making mobile data a practical reality before the full deployment of 3G and leading into the modern era of mobile internet services.  The evolution of mobile communication networks has been driven by the growing demand for efficient, reliable, and high-speed data services. Initially, networks were based on circuit-switched architecture, which was well-suited for voice communication but highly inefficient for data transmission due to dedicated channel allocation. With the advent of the internet and data-driven applications, a shift towards packet-switched architecture became inevitable, as it allowed dynamic bandwidth utilization, higher efficiency, and support for bursty data traffic. Frequently known as 2.5G, the introduction of General Packet Radio Service (GPRS) accelerated this change drastically by enabling continuous connection and marked a major departure. arrival of mobile internet connectivity. Improved Data Rates for GSM Evolution (EDGE) improved spectral efficiency and data rates over GPRS, therefore bridging the gap between 2G and 3G networks. Together, GPRS and EDGE transformed how people utilized early multimedia services, visited the web, and sent emails using mobile devices, hence creating the foundation for foundation for contemporary high-speed mobile internet infrastructure. Early mobile telecommunication systems were based on circuit switching, which allocated a fixed path to every call. Although effective for voice, the approach was inappropriate for bursty data traffic. The advent of packet switching allowed data to be transmitted in small packets, enhancing bandwidth usage and paving the way for IP-based mobile communications. The GSM network architecture, initially intended for circuit-switched voice, was extended to accommodate packet data with the advent of GPRS (General Packet Radio Service). GPRS added new network components—SGSN (Serving GPRS Support Node) and GGSN (Gateway GPRS Support Node)—to handle IP-based traffic and offer "always-on" connection.  Research indicates that GPRS provided data rates of up to 115 kbps, revolutionizing users' experience and facilitating early mobile Internet connectivity. GPRS, meanwhile, battled high latency, low throughput, and best-effort quality of service. To solve these, EDGE (Enhanced Data rates for GSM Evolution) was created as an air-interface improvement employing higher-order modulation (8-PSK) and adaptive coding systems. EDGE Maintained backward compatibility with GSM infrastructure while up to three times greater spectral efficiency was achieved. Comparative studies point out how GPRS and EDGE signaled the critical change from circuit-switched to packet-switched networks. While falling short for multimedia and real-time applications, they allowed for more effective usage of radio resources and IP-based services, therefore driving 3G and 4G all-IP architectures' development. Modern studies expand this development to mobile edge computing (MEC), where computing and storage are located near to users to lower latency and improve QoS. MEC follows the trend toward distributed, packet-based systems started with GPRS, even if theoretically different from GSM EDGE. In summary, the literature confirms that the move from circuit-switched to packet-switched data in GPRS and EDGE fundamentally reshaped mobile networks, enabling scalable Internet access and forming the basis for future mobile broadband systems.

2. Circuit Switching

A circuit-switched network creates a dedicated physical channel between two ends for the entire course of a communication session, maintaining a steady connection and guaranteed bandwidth. It operates in three steps: Connection Establishment, where a dedicated channel is established; Data Transfer, where data is carried over the reserved circuit; and Disconnection, where the channel is released to be reused. Although it offers dependable, uninterrupted data transfer for uses such as conventional voice calls, it is inefficient because it has long setup times and spends wasted bandwidth while idle, particularly for busty data traffic. Early analogue telephone systems are the quintessential circuit-switched network. Switches inside the telephone exchanges produce a continuous wire circuit between two phones for as long as the call continues. In circuit switching, the bit delay is consistent over a connection (in contrast to packet switching, when packet queues might produce fluctuating and perhaps endlessly long packet transfer delays). Because it is protected from usage by other callers until the circuit is released and a new connection is established, no circuit may be harmed by opposing consumers. The channel is still reserved and protected from competing users even if no real conversation is happening.  Though circuit switching is usually used to link voice circuits, the idea of a dedicated path continuing between two communicating nodes or parties can be spread to denote material apart from voice. The benefit of employing circuit switching is that it enables continuous transfer without the overhead related with packets, therefore maximizing available bandwidth for that communication. One downside is that it can be rather ineffective since other links on the same network cannot utilize unused capacity guaranteed to one connection. Furthermore, if the circuit is broken, calls either cannot be made or will be lost.

Fig1: scientific circuit-Switched diagram

2.2 Working of Circuit Switching                            

1. Establishment Phase:

A user initiates a connection by sending a request to the network. The network then sets up a dedicated, end-to-end path using a series of intermediate switches. A connection request is sent, and an acknowledgment is received, confirming the path's availability. 

2. Data Transfer Phase:

A special circuit is set aside between the source and destination nodes once the link has been created. Resources (such as bandwidth) are strictly assigned for the duration of the connection; data and voice both traverse this fixed path.

3. Disconnection Phase:

The circuit is unplugged and the reserved resources are released when the communication ceases, hence making them accessible for other connections.