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Overview

The following information is a compiled resource list which offers various explanations on the assorted networks, there taxonomy and functions.

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). Currently (2015) several modems have been released permitting carrier aggregation on two carriers, permitting data rates up to 200Mbps. It's important to note that currently both carriers must be transmitted from the same base station - it is not possible to pick up 700MHz B28 from one base station and aggregate with an 1800 or 2600MHz band from another base station.

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.
In this guide we take you through the installation of a pair of 17dBi grid antennas on a rural property to provide an ultra fast 4G connection.

Fast Wireless Broadband in Rural Areas

One of the major issues facing many residents in rural communities in regional Australia is the lack of high speed broadband internet services. Many areas have older generation cell towers limited to basic 3G HSPA services, which while providing a usable connection during the day, quickly become congested during peak hours - late afternoon and night. 3G congestion is something most of us are all too familiar with, it's something that affects even those of us with a strong signal - the typical symptom is noticing your connection suddenly drop from full strength to low strength, stall between page loads, or even completely drop out requiring you to disconnect and reconnect manually. While a 3G/Next-G antenna can help by allowing you to lock on to a less congested tower, or by improving signal quality to maximise coding rate, generally there's just not a lot you can do - you're stuck between a rock and a hard place. But there's some good news, Optus and Telstra's continual expansion of high speed 4G wireless broadband means a fast reliable connection might be just over the horizon (literally!). To receive a 4G signal inside your house, you typically have to be within about 3-5km of a 4G cell tower depending on what's between you and the tower. But receiving a 4G signal outside or on your roof is actually quite easy out to about 7-12km, and much further with a strong antenna! When you start talking around the 15-30km range this is where terrain comes into play; the high frequency used to carry 4G doesn't bend particularly well around hills and diminishes quickly through dense foliage. Over these distances you either have to be quite lucky, for example either you or the tower are on a hill, the terrain between is quite flat, or you have to be willing to gain a bit of height by using a large mounting pole.

Step 1 - Assessing the Situation

The first step to solving any problem is identifying the issues and assessing your surroundings. A friend of mine has a property about 14km west of Mackay (north/central QLD) in the cane paddocks which cannot get ADSL or cable Internet. As an avid online gamer his only option was to subsist with high ping rates and unreliable speeds often throwing in the towel and driving into town to use a mate's ADSL. If you've had a quick look at the 4G coverage maps and think you might be in range, the first thing to do is locate your nearest 4G towers. You can do so by following our Cell Tower Locating and Locate a 4G Tower guides which will help you not only pinpoint the 4G tower location, but also work through a basic path profile to determine if there's any hills in the way. Of course Google Earth is only a very basic tool, if you're serious about investigating 4G you should look at having a detailed site assessment done. By using our RF modelling tools we determined that there was indeed a 4G tower in range located on Milton St which appeared to provide a glimmer of 4G between two hills. Rural 4G LTE propagation non line-of-sight transmission 4G blocked by hills double order diffraction[1] You can see here that signal levels appear surprisingly good, but keep in mind RF propagation just looks at total power level and not whether the signal can be read. In this case the high figure is caused by double-horizon diffraction[1] (additive scattering) which sometimes results in higher RSSI (total power level including noise), but does not improve our RSRP (readable signal). Here's a good tutorial on edge diffraction. fresnel zone clearance LTE While this location doesn't have line of sight, our propagation model suggests that there is a reasonable potential for 4G. So without further adieu we got stuck into the installation.

The Installation

Given the 14km distance and that there was only one cell tower in range the best antennas for the situation were 17dBi grid parabolic antennas. Because his house did not have line of sight to the 4G tower we needed to install the antennas as high as practically possible - in this situation the higher you can raise the antenna the better signal becomes (the clearance distance was 44m above ground!). Some initial tests with a temporary tripod helped us determine whether 4G could actually be obtained, and after aligning to a rough angle we immediately saw speeds between 20-30Mbps with 1-2 bars of service. An old satellite dish mount on the peak of the roof was chosen to be the final installation mount. Some old water pipe lying about made for an excellent extension pole, slotting directly into the satellite mount.
Aligning a 4G Antenna
Because we managed to receive 2 bars of signal it was very likely our modem would switch on MIMO - the use of two antennas to double download speeds. In order for the modem to distinguish between the two data streams on the same frequency the antennas need to be rotated to 45 and 135 degrees to match how the cell tower is broadcasting the slant polarity waves (think polarised sunglasses). You can read more about how MIMO works here. Mounting the antennas in this fashion is a trivial task thanks to the supplied slant-polarity brackets. Now comes the most difficult task - aligning the antennas to the cell tower. While our RF modelling (or your Google Earth profiling) gives an exact azimuth/bearing to point the antennas to, because compasses give magnetic north (not true north) and iPhone/Android compass apps fluctuate about, you often need to align them by hand. The easiest way to do this is simply by trial and error - align the antennas in the general direction and run a speed test via www.speedtest.net. Rotate the antennas by a fraction, and then re-run the speed test. Continue this process making notes of which position produced the fastest speeds, or the most stable speeds. When the antennas are correctly aligned you should see a reasonably consistent speed test - if they're out of alignment you'll notice the speed test jumping about and carrying on (caused by a multipath signal). 4G speed test alignment If you're tech-oriented the best way is to use the signal meter figures provided by the modem. We're using a Telstra 320U 4G modem, which has an inbuilt hyperterminal that we can send a few simple commands to, that gives us some very detailed signal level information. Follow this guide to learn how to bring up the modem terminal. The command we're interested in is the AT!GSTATUS? command. The two measures we're interested in most are the RSRP and SINR figures. RSRP is our signal code power (power level of readable LTE signal) and SINR is our signal-to-noise ratio. AT!gstatus? AT Command Telstra 4G USB This is from a different installation, our RSRP was -103dBm Because RSRP is a negative value, we want to increase it to be less negative (ie closer to zero). -110dBm is a poor signal, and -80dBm an excellent signal. To align the antennas using these figures, rotate the antenna 1-2 degrees at a time, pausing to run the AT!GSTATUS? command. Once RSRP is maximised you want to make very small corrections to maximise SINR (the higher the number the better).
The Results
Our speeds weren't particularly great, sitting at around 30Mbps. This was disappointing but it suddenly dawned upon us that the grids were tilting a fraction below the horizon! Because this was a non line-of-sight connection all the radio waves reaching us were being diffracted off the hills, so we tilted the grids about a degree or so upwards and the results were immedate.. 50-65Mbps!

Finishing Up

As a qualified tradie, my friend was more than confident in completing the rest of the installation on his own. We were using two 10m LMR400 extension cables (which were carefully taped to waterproof the connection, and secured in place via zip ties) which were run through the roof by drilling two 11mm holes in the Colorbond roof, running through the crawl space and down into the awaiting 320U modem and Ethernet router. [1] Lakulish Antani, Anish Chandak, Micah Taylor, Dinesh Manocha, Efficient finite-edge diffraction using conservative from-region visibility, Applied Acoustics, Volume 73, Issue 3, March 2012, Pages 218-233, ISSN 0003-682X http://www.sciencedirect.com/science/article/pii/S0003682X11002611
You might have noticed your new wireless broadband modem for some reason has two ports to plug in an antenna. So which one do I use, and what on earth do I need two for?

MIMO - Multiple In Multiple Out

In this guide we're going to give you a basic understanding of MIMO technology, hopefully without getting too technical. If you're unfamiliar with how your mobile phone or wireless internet USB stick works you might wish to read this guide first. Since the beginnings of radio technology we've become accustom to a mobile phone or UHF radio transmitting with a single antenna. This transmission travels through the air and is received by a much larger antenna on a phone tower, which in turn rebroadcasts the signal to your intended destination. For transmitting a phone call this technology is simple and effective. However with the increasing demand for faster and more reliable 3G wireless internet, which works in the same way as a voice call, more complex methods of transmitting were needed. If you've been using 3G internet for a few years now you would have noticed the claimed top speeds rapidly increasing - starting around 3.6Mbps for the first series of mobile broadband 'sticks', to 7.2Mbps around 2007, to 21Mbps in 2008, to 42Mbps shortly after, and now 100Mbps with the 4G introduction in late 2011. Of course it's unlikely that you've ever actually experienced such blisteringly fast bit rates, but most people will have experienced a noticeable jump in speed when changing to a new modem.

How do they make such incredible jumps in speed?

Increasing speed is a tricky business - in the theoretical world the biggest factor limiting speed is bandwidth. Each phone tower has a given total width of frequencies it can transmit on, with each person that connects being allocated a small channel of a certain width. This means that each tower has a limited number of customers it can service before becoming congested. So the most obvious way to increase speed would be to give each customer a wider range of frequencies to transmit on, but this means less people per phone tower, which means building more phone towers, which is expensive! Instead, the first step in increasing speed is to exploit the other factors aside from bandwidth. 3G technologies like HSPA take advantage of digital modulation techniques like Quadrature Phase Shift Keying (and many other tricks) to increase the symbol rate, which is the second major factor that limits speed. Speed is also limited by Signal-to-Noise ratio, to which we can increase the power (or loudness) of the transmission so the phone tower can 'hear' us better, but this results in quickly diminishing returns. Once we've squeezed out all the performance we can from antenna-to-antenna transmission we have to approach the problem differently. This is where MIMO comes in to play - if we're unable to improve air transmission, why not increase the number of antennas? mimo streams of data By using multiple antennas we can forget about the difficulties in transmitting over air and instead place the burden on the signal processing hardware in your modem. Because all the antennas transmit at the same frequencies, no extra per-user bandwidth is required from the phone tower. Spatial Multiplexing is a set of clever modulation techniques that allow us to transmit independent streams from multiple antennas on the same frequencies without garbling the information we send. mimo signal processing [2] The above diagram demonstrates how we can shift the performance burden onto the signal processing hardware, which splits the data stream at the link layer into frames that are then encoded, modulated and mapped to the outgoing antenna. The receiving antenna performs the above tasks in the reverse order, recombining the (hopefully error free) frames into the original data stream. 4G cross polarisation x-pol 45 135 degrees 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 (Port 1 on Sierra Wireless modems).

MIMO Antennas

To work out whether the towers in your area support MIMO, check out the Telstra Mobile Broadband Coverage Map. The darkest blue colour indicates 4G 100Mbps rated areas, which uses 2x2 MIMO to deliver its speed. The lighter blue area indicates 3G 42Mbps DC HSPA+ areas, which doesn't use MIMO, but uses two channels on the one antenna to deliver faster speeds. telstra mimo coverage map To take full advantage of MIMO (currently used in 4G LTE communications) two antennas must be used. When installing directional antennas like a yagi antenna, the first antenna must be rotated horisontally to a 45 degree angle and the second to a 135 degree angle. This is because of "polarisation diversity". LTE uses polarisation diversity to help distinguish between the two data streams sent from the tower. When outside a MIMO area most modems can still benefit from the use of dual antennas. 3G services can use advanced receiver diversity techniques which utilise a second antenna to capture delayed signals and higher quality radio transmissions, and the two streams combined via MRC. Performance improvement is most commonly observed in spatial-dispersive multipath environments where signals are scattered across a physical distance. DC-HSPA+ services can benefit when carriers are broadcast on separate polarities, allowing antennas to be better matched to the polarity of the target carrier. More advanced receiver types can use linear equalisation and decision feedback equalisation techniques in an attempt to minimise inter-symbol interference. Having two antennas permits a somewhat 'stereoscopic' view of interferers, allowing some advanced receivers to adjust combining coefficients to set a null in the direction of an interferer. When using only one antenna ensure it is connected to Port 1 of the modem, which is often labelled on the plastic/rubber tag covering the port.

Helpful Resources

[1] D. Halperin, W. Hu, A. Sheth, and D. Wetherall, 802.11 with Multiple Antennas for Dummies, University of Washington and Intel Labs Seattle. [2] D. Gesbert, and J. Ahktar, Breaking the barriers of Shannon's capacity: An overview of MIMO wireless systems, Telenor's Journal: Telektronikk. [3] http://www.profheath.org/mimo-communication/single-user-mimo/
by Network Engineer for Telco Antennas.

Fastest Telstra 4G Speed

One of my quests over the past few weeks has been to test the upper limits of the Telstra 4G LTE network. My interest was to get as close to the 151.2Mbps theoretical maximum[1] (physical layer) as possible - here in QLD we are lucky enough to be provided 15MHz of Telstra 1800MHz spectrum so our theoretical max is slightly higher than our New South Welshman and Victorian counterparts (10MHz bandwidth = 100.8Mbps theoretical maximum). For an explanation on calculations see the bottom of the page. As you might have guessed that sort of speed is completely off the table for any real world transmission - as a deployed LTE-A service will have it's bandwidth (total resource blocks) eaten up by channel overheads (such as PDCCH, PCFICH, PHICH, PBCH) which reduce peak physical layer speeds down to between 107-129Mbps (PDCCH can consume 1-3 symbols per resource element). The remaining resource blocks are then shared out between all the users on the cell tower, which means to achieve anywhere close to these figures we need to minimise the number of users on the tower. To approach this theoretical limit our next step is to improve channel quality. A good metric is our RSRP and SINR figures obtained from the modem's AT command interface. The RSRP figure indicates the received signal strength in dBm, and SINR indicates signal to noise ratio. Maximising our received signal power (RSRP) and reducing noise (SINR) is important to allowing our modem to negotiate a higher order of modulation, changing from QPSK -> 16QAM -> 64QAM -> 64QAM + 2x2MIMO as our channel quality improves. Once we've obtained 64QAM and engaged both radios the next step is to push our coding rate. Coding rate refers to the amount of redundancy added to our transmission at the physical layer and is given as a coefficient between 0-1. This redundancy is designed to protect our physical layer frames from errors - note the distinction here, coding rate only deals with physical layer errors, retransmissions may still occur at the upper levels. Our coding rate is increased by maximising RSRP and SINR - providing an ultra clear signal, allowing us to pack more data into every block.

The Test

To limit the impact of other users I conduct tests between 1am and 2am. This is not perfect, my hope here is that people generally have better things to do at 2am. Speedtest.net was used as it forms the generally accepted and comparable metric. I modelled 1800MHz transmission based on ACMA data, including antenna type, azimuth, AGL, downtilt, etc. to pick ideal locations where I'm likely to get a nice clean signal. Testing at a few different areas produced RSRP readings between -40 to -60dBm. Little improvement in speed was gained by achieving RSRP above -59dBm, the majority of improvements thereafter were made by maximising SINR. Results were highly variable due to minor tower loading (as some late night users jumped on the tower), but were consistently around 87Mbps when I had it to myself. Peak application layer speeds were around 88Mbps, with the highest being 88.25Mbps. In conclusion 90Mbps appears to be pushing the limits on 15MHz - it took over an hour to push from 87.95Mbps to 88.25Mbps, with different locations tested. The main limitation appears to be pilot interference and noise, reducing our coding rate. An important point to make was that the tests performed with Oolka (www.speedtest.net) were not of sufficient duration, as speeds were continuing to climb as the modem conversed with the eNodeB. Since this test was conducted, our fastest QLD speed achieved is now 102.7Mbps from a newly activated 4G tower in an isolated area. Faster speeds are achievable with an LTE category 4 device in areas with 20MHz of spectrum.
Equipment
2x 17dBi 1800MHz Grid antennas - arranged in 45/135 degree slant polarisation 2x LMR400 N to FME 5m cables 2x TS-9 to FME patch leads Telstra 4G 320U USB (LTE category 3) Theoretical Maximum Calculations Given 15MHz of bandwidth we have 75 Physical Resource Blocks (PRBs), each consisting of 12 subcarriers with 7 symbols per subcarrier assuming normal cyclic prefix. Each subcarrier/symbol combination is called a Resource Element and can be transmitted in a 0.5ms slot. We use 64QAM so we encode 6 bits per symbol, and 2x2MIMO so we double our data rate. Therefore it is simply a matter of multiplication: 75 x 12 x 7 x 2 x 6 x 2 = 151200 bits per millisecond 151200 x bits/ms x 1000 x ms/s = 151200000bps 151200000bps = 151.2Mbps [1] Harri Holma and Antti Toskala, LTE for UMTS: OFDMA and SC-FDMA Based Radio Access (Chichester: John Wiley & Sons, 2009), 214.

How to force modem into 4G

This page will show you how to force your Telstra/Bigpond Sierra Wireless 320U or 760S to lock on to Telstra 4G LTE 1800MHz. Locking on will allow your modem to ignore all other available networks, which is exceptionally handy in low signal areas or where a nearby 3G or Next-G tower is overpowering the available 4G. You won't need any special tools or skills, just the software that comes with your modem and a dash of common sense.

Step 1.

Open the Bigpond connection manager. Click Tools Now hold the Shift key and click Options (hold Shift + click Options) telstra bigpond 4g connection manager

Step 2.

There will now be a new tab revealed named Diagnosis. This tab displays all sorts of handy options but the one we're interested in is the Modem Terminal button. Click the Modem Terminal button. diagnosis tab and modem terminal button bigpond connection manager

Step 3.

Once the new screen has popped up, type AT!BAND=03 into the text box at the bottom and press send. This command sets the operating band to operate on LTE 1800MHz only, and ignore everything else. modem hyperterminal send AT command to bigpond 4G modem This process can be undone by typing the command AT!BAND=00 which switches the modem back to searching on all bands (it's default setting). Enabling SMS on the Telstra 4G 320U USB Modem Just another handy little tip, to enable SMS on the Telstra 4G modem we can repeat the above process but sending the following two commands instead: AT!ENTERCND="A710" AT!CUSTOM="LTESMS",1 Then unplug the modem from your computer and reinsert. You will now notice the messages icon will be enabled. text messaging from telstra 4g wireless modem modem terminal Thanks to JRZ on Whirlpool for suggesting this tip! (Ref: http://whrl.pl/RdcWtb)

Advanced Users

For remote operation, programming, or any other situation, the modem can also be operated over a COM port by using a program such as HyperTerminal, or the RS232.h header file when programming. You can locate the COM port via the device manager and scrolling down to Ports (COM & LPT), and looking for Sierra Wireless AT Command Interface. Note that you'll need to send AT+CFUN=1 to turn on the radio before sending further instructions.