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Australian 4G Explained

4G - Telstra's next major infrastructure upgrade.

Initially available in major cities, airports and selected regional areas in October 2011, Telstra's 4G network offers significantly faster speeds, lower latency, and reduced network congestion. The latest upgrade to the Telstra 4G network (coined 4GX) and release of Category 6 LTE devices in 2015 will see peak speeds of up to 300Mbps in enabled areas.

The 4G network is based on LTE - 3GPP Long Term Evolution. LTE is a series of upgrades to existing UMTS technology and was initially rolled out on Telstra's existing 1800MHz frequency band. This new network boosts peak downloads speeds up to 100Mbps and 50Mbps upload, latency reduced from around 300ms to less than 100ms, and significantly lower congestion.
Telstra LTE 4G modem

Telstra vs Optus vs Vodafone - Network Comparison

All three major network operators in Australia provide 4G networks. Telstra currently has the largest network with 4G being available in all metro areas, including over 300 regional towns across Australia. Optus is heavily investing in their 4G network and is fast closing the gap, with plans to cover over 200 regional towns by early 2015. Vodafone is working hard on their network, but at the moment is only available in select areas in capital cities.

Telstra 4G and 4GX

As of early 2015 Telstra will be launching their 4G network expansion which includes two additional carrier frequencies - 700MHz and 2600MHz, on top of their existing 1800MHz network. The expansion, coined 4GX, will provide significantly more capacity, meaning less congestion and faster average speeds. Using Carrier Aggregation the 4GX network will also allow compatible 4G modems to operate on all three frequencies at once, increasing maximum peak speeds - theoretically as high as 300Mbps (using 3x 20MHz carriers).

Optus 4G

Just like Telstra, Optus too have begun the rollout of their 700 and 2600MHz LTE networks which will support carrier aggregation, providing faster average and peak data rates. Both networks aim for 90% population coverage in 2015. The network gets a little confusing with Optus also operating a 2300MHz 4G service in select areas such as Canberra.

Vodafone 4G

Not having purchased any 700MHz spectrum, Vodafone have instead decided to convert their existing 850MHz 3G network into a 4G network instead to compete with the new Telstra and Optus long range networks. This network runs in parallel with their existing 1800MHz 4G network.

What's so great about the new frequency bands?

With so many changes to 4G in Australia, it's an exciting time to jump on board a 4G network. We're about to see the 700MHz 4G network switched on by Telstra and Optus in early 2015 (with some locations already having early access). This network is going to be a game changer - one of the major drawbacks with the older 1800MHz 4G network has been its high carrier frequency doesn't travel particularly far and doesn't penetrate well indoors. 700MHz on the other hand having such a low frequency travels significantly further, bends around and behind hills, and penetrates much easier inside buildings, providing coverage similar to Telstra Next-G - meaning high speed data will now be available as far as you can make a phone call (in switched-on areas).

There's not a lot of publicity about the new 2600MHz 4G network, but despite having a very short range it's important to help reduce congestion in densely populated areas such as city centres where the operation of a long range transmitter would have considerable self interference (due to the long reuse distance required).

What about backhaul

With a massive increase in speed, how can the cell tower transmit and retrieve all this extra data from the Internet? Your 4G connection is only as fast as what the base station can provide you. Older EDGE or HSPA networks could get away with E1 or microwave backhaul links (ie the link that connects the tower into the wider network), but LTE services require a far more advanced Ethernet-based backhaul link, generally by Optical Fibre. Unfortunately this is a key limitation on how fast your local base station can be upgraded to provide 4G. The transition from circuit-switched to packet switched (IP based) networks affords better QoS (through MPLS and other link/network layer protocols) and significant reductions in latency.

4G Antennas

It might seem obvious to some, but it's important to understand that your carrier's 4G network only provides high speed Internet. Your mobile phone or modem might display '4G' on the box or on its case, but this simply means that it can connect to the Internet via 4G in enabled areas. Please check your carrier's Coverage Map to determine whether you will be operating within their 4G coverage zone before going any further.

If you're in a rural area or travelling you do not need a 4G antenna, please visit the section of our website that best matches your application.

What type of antenna?

If you've read the previous section on 4G Equipment, you'll know that as of 2015 there are two new frequencies we must consider - 700MHz (Band 28) and 2600MHz (Band 7).

As mentioned previously the 700MHz is a long range, wide coverage network. The downside of this however is that the base station can still only fit the same number of subscribers, but now covers a significantly larger geographic area. What this means is that the expectation is that the 700MHz will be a lower speed network due to the higher number of expected users, so to achieve the best speed possible we have to get tricky.

Multiband Antennas

While the network configuration is already set with a band preference of 2600 first, 1800, and 700MHz last, higher performance will be achieved by selecting an antenna that has a higher gain in the upper bands so that the modem may achieve a connection to these networks to provide a higher capacity connection.

To take advantage of these network features you'll notice many of the below antennas operate across multiple bands, usually in the form of a high performance panel or LPDA. The downside of all multiband antennas is that to increase the operating bandwidth you must reduce antenna gain, or, have a very large and heavy antenna. To retain practicality, our multiband antennas have a maximum gain of about 10-11dBi. We do supply a 13.5dBi 700-2700MHz panel antenna however measuring 680 x 425 x 135mm weighing over 12kg it's simply impractical for most rooftops.

High Gain Antennas

Long range 4G connections are possible using high gain antennas. High antenna gain can only come at a cost of frequency bandwidth, meaning at ranges in excess of 20km you will have to pick one frequency to operate on. Because not all 4G base stations will broadcast all 4G frequencies it's important to do the research and find out what frequency is being operated at the target base station before selecting an antenna. Because of the high degree of complexity we can take care of this for you by undertaking a Computer Modelling Survey. Otherwise you'll find a range of high gain dish, grid, and yagi antennas under the Outdoor section below.

4G bandwidth (ie the width of frequencies we can send and receive on) is critical in supporting high speed and a high number of users. Because in order for your connection not to get confused with someone else's, each user is allocated a small sliver of frequencies that they can transmit on and nobody else can. You'll notice this most during peak usage hours, where as more people start using the tower it will reduce the width of your (and everyone else's) sliver of frequencies, resulting in each person getting a reduced download/upload speed.
Naturally this is a very simplified explanation (for more info read up on OFDMA and SCFDMA) but for our purposes it will suffice.

MIMO

The second most important feature of a 4G antenna is the capability to operate in MIMO.
4G cross polarisation x-pol 45 135 degrees
4G uses a technology called MIMO "Multiple In Multiple Out" where your modem uses two separate antennas at once to deliver super fast speeds.

Normal 3G and Next-G signals are broadcast vertically polarised, where the wave travels "up and down". LTE MIMO waves are slant polarised where each wave is rotated 45 degrees from the horizontal, mirrored so the first is at 45 degrees and the other at 135 degrees. This smart little trick is called polarisation diversity and allows your modem to distinguish two independent streams of data over the same frequency allocated by the cell tower.

Because our modem has two internal antennas each responsible for receiving one stream of data, it is absolutely crucial we have two separate external antennas. We cannot use a 'Y' patch lead or some other trick to connect both ports of the modem into one antenna, nor can we connect both external antennas into one port.
4G LTE MIMO in low signal areas
It is important to know MIMO is switched on and off by the modem. The decision whether to use MIMO is negotiated with the cell tower, whereby the quality of the received and transmitted signals are assessed (a metric known as CQI). When signal strength or quality is low it's difficult for the modem to distinguish between the two data streams, so when signal levels drop below a certain threshold level, MIMO is switched off and the modem operates with only one antenna.

Interference - Why the fuss?

The distinction between signal quality and signal strength is not to be overlooked. Strength refers to the total available power (amplitude) of the measured waveform, whereas quality refers to the degree in which information can be correctly interpreted from that waveform. The measure of most importance is the C/I+N Ratio (or SINR) as 4G negotiates its radio bearer index based off the strength of the interpreted carrier signal over the interference+noise level (well, indirectly..) - so the lower the interference, the higher the C/I+N, and consequently the faster the modulation and coding scheme.

The most prominent source of interference on a 4G network is self-interference - i.e. interference from other sectors on the base station, and other base stations themselves. Other sources of interference can be systematic (natural) and include thermal, gamma radiation, or hostile (unnatural) including machinery, high voltage transmission, illegal boosters, etc.

How does an antenna help?

Beamwidth. By focusing the transmission beam to a particular direction we increase strength in one direction at the cost of all others. We can use this to mitigate unnatural sources of interference such as nearby machinery generating wideband noise, or minimise self interference by decreasing strength in the direction of the interfering base station - all while simultaneously increasing strength in the direction of the target base station. As you can see we've increased C while simultaneously reducing both I and N, resulting in a higher MCS index (called a Radio Bearer index in LTE), resulting in higher symbol rate and higher code rate.