Both GSM and CMDA are in their twilight years since most operators are moving to 4G and 5G. Companies such as T-Mobile, AT &T and also Total Wireless 

carrier Verizon has confirmed plans to shut down their 2G/3G GSM networks in a move to advance to the better and more efficient 4G and 5G technology.

What is GSM?

GSM is an acronym that stands for Global Positioning System for mobile communication, and it is a standard protocol used in digital cellular networks by mobile devices. Initially, during its inception, it only offered voice telephony service, but later adopted data communication services. It was however succeeded by 3G technology. It was intended to be a secure wireless system using a pre-shared key, challenge response and over the air encryption.

It uses cryptographic algorithms for the security of the network architecture

GSM enabled data communication via circuit switched network technique, whereby a dedicated line or channel is left open during the entire period of transmission. This system uses a Subscriber Identity Module Card(SIM card) that contains a phone book and subscription information. The network structure of GSM is divided into discrete sections namely:

Network Switching Subsystem(NSS)- is also called the core of the network and provides main control and interfacing for the whole GSM network.

Base Station Subsystem (BSS)- part of the network that communicates with devices on the network through the Base Transceiver Station(BTS) and the Base Station Controller (BSC)

Operation and Support Subsystem (OSS)- controls and monitors the overall GSM network and also controls the traffic load of the Base Station Subsystem.

GSM services

Voice was the major service offered by GSM at its inception. The speech to be transmitted is first encoded digitally, sent through the communication channel and then decoded at the receiver by a vocoder which is a decoder for voice signals. Data include Teletext, videotext and facsimileShort Message Service (SMS)- has morphed excellently as part of GSM services and is popular since it is simple and cost effective. International roaming service that allows a user to use their mobile phone for services such as calls, text and internet use even when in another countryGeneral Packet Radio Service(GPRS) is-a service that uses packet switched data to communicate over the GSM network. Despite being slow, it enabled data to be incorporated as a main part of the GSM system.

Some limitations of GSM include:

Need for many repeaters-mobile carriers needs to mount several repeaters to boost both the signal strength and its coverage. Delay-due to multiple mobile terminals accessing the same bandwidth, GSM networks experience a lag in bandwidth especially with new users joining the network. Electronic interference-GSM networks have been known to interfere with other electrical signals such as those coming from watch towers in airports due to the use of pulse transmission technology.

What is CDMA?

Code Division Multiple Access(CDMA) is a multiplexing technique in which users in a given communication channel are given access based on the code of the channel they want to access. The communication path is divided into separate channels, each with a unique code for multiple access by many users, and this unique coding is usually for separation purposes.

Signals are encoded with their code sequence. Many transmitters are capable of sending data through one channel, permitting the users of this network to share a range of frequencies(bandwidth). This process of combining multiple signals from multiple transmitters via one channel is known as multiplexing. 

At the receiver end, the multiplexed signal is separated into its constituent original signals using a demultiplexer, before being sent to their respective receivers. 

Some types of Multiplexing techniques include:

Frequency Division Multiplexing- multiple signals are combined for transmission on a single line or channel with each signal assigned to a different frequency or subchannel within the main channel

Wavelength Division Multiplexing-multiple signals of different carrier wavelengths are channelled through the same medium. 

Time Division Multiplexing- all signals operate using the same frequency or bandwidth but at different time slots.

Code Division Multiplexing- channels are given unique codes and users access them based on the codes provided(discussed above)

Summary:

Total wireless service runs on Verizon’s network, which is a Code Division Multiple Access(CDMA) network. Some of its advantages are :

Cheap individual plans that are affordable to the majority 

Unparalleled network coverage 

It however has two main challenges which are:

Data deprioritization- the deliberate slow down of data speeds by the network owner

Limited full speed- though the data may be unlimited, it will be at very low speeds i.e 2G