 |
|
|
The AMPS analog cellular system in Australia has a serious Year 2000 problem. So serious that the system may be off the air permanently after midnight, December 31st, 1999. This is not due to an insolvable software problem, or a dangerous Y2K computer virus, but due to an Australian government law. On January 1st, 2000, two million Australians will be looking for a new wireless system and a multi-billion dollar investment will be scrapped. That is, unless the Australians who are fighting for retention of their preferred system get their way.
Apart from the single 800 MHz AMPS analog system in Australia, operated by Telstra (with Optus acting as a reseller), there are also three 900 MHz GSM systems operated by Telstra, Optus and Vodafone. Together they account for about 3 million subscribers. Australia is also in the process of auctioning 1800 MHz PCS spectrum and will auction the AMPS spectrum once it is abandoned.
The closure of the AMPS system was promised to the GSM operators by the Australian government before they started service in 1993, and is written into law, making it difficult for the government to wriggle out of their promise, even if they wanted to.
In today’s environment of free, unfettered competition, Australia stands alone in eliminating a viable wireless system that provides a useful service and that is not causing any harm. How did this come about?
The first problem may have been caused by the AMPS carrier itself. While the technology provides for two independent frequency bands, this possibility was compromised in Australia when Telstra, officially the ‘A’ band carrier, started using voice channels in the ‘B’ band in Sydney, without permission. It would have been possible to slap them on the wrist and make them live within their assigned frequency band through better RF planning, but this was never done.
This was probably not the only reason that a competing AMPS carrier was never licensed, the lure of digital was also strong. At the time that decisions were being made in the early 1990s, GSM was the only option for a digital system; D-AMPS and CDMA were not yet mature.
As an incentive to raise interest among potential GSM operators and increase the license prices paid by the new operators, the government guaranteed in legislation that the existing AMPS network would be retired by the turn of the century. At this time, Telstra would be put on a level playing field, and all three operators with mobile networks would have approximately equal thirds of the GSM 900 spectrum. The Australian government obviously did not believe that the analog system would have any advantages over digital by the year 2000, and therefore did not consider that terminating it would cause problems or raise serious opposition. Now, however, the government is legally bound to pull the plug on AMPS, unless the competing GSM carriers give permission for it to continue – something that they appear unwilling to do.
APUMP (The Association for the Protection of Users of Mobile Phones) is an organization with the sole aim of preventing the closure of the analog network by having the Australian government “repeal Sections 360 and 361 of the Telecommunications Act,” according to APUMP president Boyd Munro. They are focusing on public education and political lobbying, with money raised from annual membership fees.
GSM phones are well suited for urban users in some ways. They provide more advanced features, such as calling number display and short message service. GSM also gives about double the capacity in the same amount of spectrum, due largely to a frequency re-use pattern of 4 (versus 7 for AMPS). Standby battery life is also often longer. However, even in cities, Munro claims that “Urban users will notice the loss [of the analog network] acutely. Trades people who rely on their mobile to receive calls from customers will notice that the in-building penetration of GSM is much worse than AMPS. People who use hearing aids will notice it because they are not compatible with GSM phones. People on the AMPS $5 and $10-per-month plans will notice it because the lowest GSM plan is $20 per month. Urban Australians who travel to country areas will notice it. Finally, people who have paid $1000 or more for an analogue phone that is suddenly rendered useless will notice it.”
In rural areas of Australia, the AMPS analog system is far superior, mainly due to significantly higher coverage, often many times the area from a single cellsite than for GSM. The big difference in cell coverage area is not due to a single factor. Analog phones use only frequency to separate users (30 kHz each), an attribute that does not change with distance from the cellsite. TDMA phones, on the other hand, use a combination of frequency and time separation. GSM provides 200 kHz channels, each of which can support 8 users separated by time. According to Frank Robert, a consultant with CommStrategies, “The time that signals take to travel from a GSM mobile to the cell site serving it is affected by its distance from the cell site: the propagation delay difference between close and far users reaches the length of the time slot assigned to a single user while he is still much closer to a GSM site than the maximum range of an AMPS site, although power in the link budget from the mobile is more than sufficient to maintain the connection. This produces a propagation delay-driven ‘hard boundary’ to GSM cell sites (and other TDMA technologies as well) not found in AMPS or CDMA. The Australian GSM carriers have reportedly obtained a variance from the GSM MoU permitting them two time slices per user which, if implemented, would slightly reduce the problem but not eliminate it.”
According to Elliott Drucker, President of Drucker Associates and a radio engineering consultant, “The limiting factor on the range of wireless systems is the Carrier-to-Noise ratio at the receiver. Assuming that the carrier parameters of transmit power and path loss are similar, noise is the differentiating factor between GSM and AMPS. GSM, with a 200 kHz bandwidth, has to cope with almost 7 times the noise found in a 30 kHz AMPS channel. This corresponds to an 8 dB difference in noise level, which can easily result in more than a 2:1 advantage for AMPS in range for rural cell sites and a substantial difference in effective building penetration.”
The coverage advantage of AMPS is multiplied because it provides more choice of cell locations. Assuming that a cellsite in the outback is intended to provide in-building coverage for a single town plus outdoor coverage in as much of the surrounding rural area as possible, a GSM cellsite can be a maximum of 5-6 miles (8-10 km) from the town, while an AMPS cellsite can be up to 30 miles (48 km) away. This provides up to 110 square miles to search for a GSM cellsite location that has the highest altitude, plus a nearby road and electricity. AMPS, on the other hand, may provide up to 3,000 square miles to search for the best location. Higher average cellsite location further increases the coverage advantage of AMPS.
AMPS systems can also take advantage of ‘skip’ on water and flat land (of which there is lots of the latter in Australia, if not the former). Because this type of coverage is not reliable, it is not shown on Telstra coverage maps. So, many people who theoretically should not have AMPS coverage in Australia, actually do (at least most of the time) have it. Under ideal conditions, Greg Young, AMPS and New Business Manager for Telstra (www.telstra.com.au) states that an AMPS site can cover a radius of 100 km, either from a cellsite on an isolated hill in an otherwise flat area, or out to sea. On the other hand, Young points out, when cells are terrain or capacity limited, GSM and AMPS coverage areas may be very similar.
APUMP has provided propagation model coverage maps for the Mt. Canobolas area (see Figures 1 and 2) which illustrate the discrepancy between the coverage provided by GSM and by AMPS. Both propagation models were calculated with the same parameters to ensure a valid comparison.
Figure 1: AMPS Coverage |
Figure 2: GSM Coverage |
 |
 |
Coverage is not only better from individual cellsites, but the fraction of Australia covered by AMPS is about 20% greater than GSM. According to Young, “AMPS covers 6% of the total area of Australia and GSM 5%, a difference of about 30,000 square miles (over 75,000 square kilometers). This difference is due to greater coverage from single cellsites and also partly because analog cellular was seen as a Community Service Obligation for AMPS, but not for GSM, resulting in AMPS cellsites being placed in some sparsely populated rural areas without an economic justification.”
The Australian government is claiming that nobody will lose cellular service due to the phase-out of AMPS. According to Warren Duncan, Manager of the Analogue Closure Education Unit of the Australian Communications Authority (ACA; www.acma.gov.au): “If anyone is receiving a [cellular] service they will continue to do so – either GSM or a retained AMPS service, but this all depends upon the outcome of the ACA review and government discussions with the carriers.” GSM carriers can agree to keep some AMPS cellsites in operation, or else, according to Duncan, “... the government may require the carriers to extend their GSM networks by additional obligations being placed on them.” This compromise would force many Australians to buy two phones as, according to Duncan, the government has not committed to making the availability of dual-mode GSM-900/AMPS-800 phones a requirement before discontinuing AMPS. And, as Young observes, the market for such phones would be limited almost exclusively to Australia. Also, because urban areas – the most profitable parts of the AMPS network – would be removed, the entire system could lose its fiscal viability. According to Young, this is a concern for Telstra. The government could be left in a situation where the AMPS system cannot afford to continue operating in the few areas where GSM carriers agreed to allow it to exist. However, agreeing to allow AMPS to operate in these areas might relieve the GSM carriers of an obligation to provide coverage, resulting in either a lack of coverage, a government subsidy for rural AMPS, or new mandates on GSM carriers that may cost hundreds of millions of dollars to fulfill.
Further in the future, the government may be hoping that satellite systems provide coverage to rural Australia. According to Tom Dale, spokesman for the Minister for Communications, “the introduction of low earth orbiting satellites is expected to deliver affordable mobile phone coverage over the entire Australian land mass.” According to an industry source who wished not to be identified, the government may subsidize LEO satellite services to assuage angry residents of the outback.
APUMP believes that loss of service will occur, and will have serious safety implications. According to Munro, “Those who will suffer most are the families of those who die because they are denied the rescue that would have reached them had the analogue network still been in service.”
The governing Liberal party government appears committed to their current course of eliminating AMPS in Australia. According to Dale, “The decision to close the AMPS network was made by the previous Labor Government. Legal agreements made at that time make it extremely difficult to reverse the decision completely.” However, Munro points out that although the previous Labor government initiated the legislation, the Liberal party voted with them, in favor of the closure, while in opposition.
The Australian government appears to have blown one chance to exert some leverage on Vodafone and Optus. These GSM carriers were relieved of their Australian ownership conditions in August 1997. This would appear to have been a perfect opportunity for a little tit-for-tat. At least one Australian politician, Independent Peter Andren, is upset at what he calls a giveaway. He made a parliamentary motion in April 1998 to withdraw this privilege from Vodafone. However, government members did not break party ranks to support him.
Another looming political problem is the pending sale of Telstra. The remaining government shares of this company will be floated after the election if the Liberal Party gets back in, to repay part of Australia’s National Debt. The value of the company could change dramatically if, after the sale, the government reverses its position on AMPS and allows the network to continue operating. This could provide windfall profits for its new owners.
The Australian government may still have a little room for maneuvering, as the Australian Communications Authority is now reviewing the shutdown of the AMPS network. According to Duncan, “The review is to be completed by 30 June 1998 and it will examine each of the 420 regional AMPS base station coverage areas to determine whether the phase out of the service would leave that area without an alternative mobile phone coverage (from GSM digital, for example), offering a quality of service and a breadth of coverage reasonably equivalent to that offered by AMPS. Once this fact finding review is finished, the ACA will be working with local councils and interested parties.” The review could be a sales pitch for the government position, or it could be an exercise in measuring the temperature in the hinterlands.
After the AMPS shutdown, the unused 800 MHz spectrum will be auctioned. The government has placed no restrictions on uses for the spectrum – it does not even have to be used for cellular communications – except to forbid it from being used for an AMPS system! The successful bidder may well put in a D-AMPS or CDMA system. This will be the best solution short of a reprieve of the AMPS closure for analog customers, because both D-AMPS and CDMA support dual-mode analog/digital phones and, according to Young, Telstra will be required to support roaming on the remaining analog cellsites. However, this will still require the purchase of a new phone, and it will cause a significant delay while the spectrum is auctioned and new urban cellsites installed.
The Australian government currently appears to be trying to weather the storm, survive the upcoming election, eliminate AMPS and move on into a future of GSM digital cellular and a variety of PCS systems. Meanwhile, APUMP is trying to turn 2 million AMPS users into political activists. Who will win is uncertain at this time, but the wireless news out of Australia should continue to be exciting until at least January 1st, 2000!
© – Copyright