From MHz to duplexing: understanding the tech behind 4G, and why it matters
We all know that 4G is the fourth generation of mobile networks; following on from 3G, and offering faster download and upload of data. 4G is a broad term that covers a variety of different standards and technologies, each with specific characteristics. In this blog I want to unpick the different technologies, some of the acronyms, the inherent advantages and disadvantages, and what Telstra Wholesale offers to our customers and why.
Not all 4G technologies are equal
‘4G’ is actually a marketing term and does not strictly refer to any one particular technology, although, over time, 4G has become synonymous with a specific technology called ‘LTE’, especially here in Australia.
In setting a standard for 4G networks, the International Telecommunications Union (the international body responsible for telecommunications) agreed a set of requirements that would be sufficiently advanced over previous 3G networks. These requirements included increasing efficiency to handle more users at higher data rates, lower latency for a more responsive internet, and support for multiple antennae at both the transmitter and receiver to improve performance. The target download rate was set at 100 Mbit/s when moving, and 1 Gbit/s when stationary.
As a result, two competing technologies evolved to meet these requirements. WiMax (Worldwide Interoperability for Microwave Access) and LTE (Long Term Evolution) are the two commercially available 4G technologies, and while there are similarities in the underlying technology, there are tangible differences in their operation and real world performance.
Internationally, LTE is the dominant 4G technology, although WiMax is still in operation. Within Australia there is a mix of technologies used by network operators, with all using LTE to power their mobile networks.
LTE has continued to evolve since its introduction. We have now deployed LTE-A – where the ‘A’ stands for Advanced – which enables devices to combine multiple frequency channels at the same time, a concept known as ‘Carrier Aggregation’. This helps provide a better experience for users with increased download speeds and fewer drop outs.
In Australia the 4G services use a variety of radio frequencies ranging from 700 MHz to 2600 MHz to deliver data. Higher frequencies are capable of higher data transfer rates, meaning users experience lower latency and fewer interruptions when streaming, downloading or video calling. However, lower bands have a longer range and are better at penetrating buildings, so the 700 MHz frequency will deliver a better all-round service when the user is indoors or underground.
As a result of these developments, Telstra’s network in Australia enjoys some of the best mobile network speeds in the world. Using carrier aggregation, Telstra has delivered some true ‘global first’ developments such as demonstrating the first 1Gbit/s speed capability on a commercial network and the first 600 Mbit/s connection on a live network.
LTE-FDD versus LTE-TDD
Of course, there is more than one kind of LTE. There are two different approaches to how the frequency spectrum is used: Frequency Division Duplexing (FDD) and Time Division Duplexing (TDD).
FDD and TDD Comparison
|Frequency Division Duplexing||Time Division Duplexing|
|Separate, dedicated frequency bands for transmitting and receiving means that devices can transmit and receive simultaneously||One frequency band for both transmitting and receiving, meaning that devices need to alternate between transmission and reception|
|Delivers the maximum speed available for the allocated frequencies||Configurable upload and download capacities, but less efficient use of the networks leads to lower maximum speeds compared to FDD|
|Broad support from device manufacturers||Limits on which devices can be used|
Delivering a great experience through an advanced mobile network
Telstra deploys 4G LTE-A FDD on a combination of 700 MHz and 1800 MHz with 2600 MHz added for capacity in selected areas, because it enables us to provide our customers with a fast, high quality network, delivering a great experience to them and their end users.
Using the Telstra network, our reseller partners can now offer excellent network speeds and coverage to their customers. Telstra Wholesale recently launched 4G for our Mobile Virtual Network Operators (MVNOs), deploying the LTE-A FDD standard to deliver typical download speeds of 2-50 Mbit/s and upload speeds of 1 to 10 Mbit/s.
We continue to invest in our market-leading network so that MVNOs can be assured they are benefiting from some of the best mobile technology available, without having to worry about the acronyms!