- Internet Frequently Asked Questions
- Types of internet access technologies
- Factors that affect your internet service
What is downloading?
Downloading is the process of retrieving data from another computer on a network, for example text, pictures or sound. Viewing a page on the internet is downloading data from another computer and contributes to any download limits placed on the user’s account by the Internet Service Provider (ISP).
What is uploading?
Uploading is the process of sending data from a computer to another computer on a network, for example, sending an email or uploading a web page. Allowing other internet users to retrieve files located on your computer, for example music files, is also uploading data.
Does ‘shaping’ affect my internet data rate?
Shaping is the practice among ISPs of intentionally reducing data rates (to approximately 64 kbits/s) when the download quota for the plan’s billing period has been exceeded. Telstra does not shape their internet service, but instead charge customers for the downloads/uploads increments above the plan quota.
Can the advertised download and upload data rate be expected?
Packet networks, including Internet Protocol-based networks (IP) such as the Internet, do not use dedicated circuits (pathways) and it is therefore impossible to categorically state what the data rate of any particular session is going to be. Reported data rates for these services are usually theoretical maximums, which may not be achievable and vary during any particular session. Many external factors outside the control of ISP may contribute to diminished data rates.
Dial-up internet access
The most common internet access technology in Australia, dial-up internet access enables users to access internet by establishing a connection through a modem that dials into the public telephone network (circuit switched Public Switch Telephone Network). This technology requires a ‘call’ to be made and establishes the data link through the voice channel of the PSTN. This means users incur any relevant calling charges (in addition to charges levied for internet access) when establishing a session and users cannot use any telephones connected to the same line during an internet session. The data rate is usually limited to a maximum download data rate of 56 kbit/s.
Integrated services digital network
Integrated services digital network (ISDN) technology provides a dedicated data service that can be used to provide voice telephony and basic data services such as internet and point-of-sale electronic payment services. It offers downstream data rates of up to 128 kbit/s. ISDN uses a unique architecture that is conceptually similar to circuit-switched networks, but it can function over significantly longer distances between the user’s premises and the nearest network point-of-presence compared with many terrestrial broadband technologies.
Digital subscriber line technologies
Various digital subscriber line (DSL) technologies are deployed in Australia, offering data rates significantly higher than dial-up internet access. DSL technologies operate over copper-pair access networks originally deployed for circuit-switched telephony (the PSTN) and exploit the significant bandwidth not used by those telephony services.
DSL technologies vary significantly in performance attributes and configuration and there is an emerging trend towards generational evolution analogous to the evolution of mobile access technologies, with the prime example being the evolution of asymmetric DSL (ADSL) into longer range and faster versions, described as ADSL2 and ADSL2+.
ADSL is asymmetrical due to the different rates for uploading and downloading data, with the upload rate usually being a fraction of the download rate. It is theoretically capable of download rates up to 8 Mbit/s and upload rates of up to 1 Mbit/s, but there are virtually no services offering download rates of more than 1.5 Mbit/s, due to the limitations of the PSTN. ADSL is historically only available up to about four kilometres from an ADSL-enabled telephone exchange.
Hybrid fibre coaxial cable technologies
Hybrid fibre coaxial cable (HFC) technologies involve the use of optical fibre and coaxial cable to carry data at high rates. The optical fibre connection forms the ‘backbone’, with coaxial cable running from fibre nodes to the customer’s premises. These networks usually support multiple service channels in the form of voice telephony, internet access and subscription television services.
Optical fibre technologies
Optical fibre cable services are regarded as the most reliable and highest data rate infrastructure available for supplying telecommunications services. While other current and emerging services may be able to deliver the same applications and content, most of these alternatives are limited in geographic range from the required base stations and the maximum available data rate. The relative disadvantage of optical fibre as a delivery system for services is its cost, because it requires trenching (digging of trenches to lay cables) and physical installation of a buried or overhead cable. It is also much more expensive to terminate. Because of this cost, at present optical fibre is used primarily for backhaul services.
Broadband over power line communications
Broadband over power line (BPL) communications is an emerging technology that uses electricity networks for the transmission of data, voice and video. Subscribers only need to install a modem that plugs into an ordinary electricity outlet and pay a subscription fee similar to other internet access services. BPL may also be used for in-building networks, such as business local area networks (LANs) and home networks. It has been deployed in four pilot projects in Australia and is currently subject to an ACMA review.
Wireless access technologies
The deployment of wireless access technology has been the most significant trend in Australia over the last few years. Mobile wireless access technologies can generally support access to a limited range of data services and applications. While second generation (2G) mobile services were designed with the primary (if not sole) intention of providing voice services and their suitability for other applications is extremely limited, other wireless access technologies were designed primarily for data services.
Wireless access technologies are grouped according to whether they enable fixed access (access from a single location) or nomadic access (access from either multiple static locations or access while mobile). Nomadic services are described as being either ‘portable’, meaning they can be moved between access points but usually not able to be used while moving, and ‘mobile’, meaning they can be used while moving.
Fixed wireless technologies
Local multipoint distribution system (LMDS) also described as ‘microwave’ services is a technology for broadband microwave wireless transmission direct from a local antenna to customers within a line-of-sight radius. LMDS is an alternative to installing optical fibre all the way to the user or to adapting subscription television for broadband internet service. Some services offer both downstream and upstream service (symmetrical service); others offer downstream only (asymmetrical service), with upstream being obtained using wire connections. LMDS is unable to provide nomadic access due to the size of the customer equipment, specifically the transceiver.
Nomadic wireless access—proprietary technologies
Two access networks offer high data rate access using proprietary portable or mobile technologies in Australia. iBurst uses smart adaptive antenna technology to provide mobile access and high data rates in the 1.9 GHz licensed band. Navini uses a beam-forming, diversity path loading technology providing a nomadic broadband system in the 3.4 GHz licensed spectrum band
Nomadic wireless access—open standards technologies
Some access technologies are based on standards developed through cooperative projects managed by Institute of Electrical and Electronics Engineers (IEEE) 802 standards working groups.
The 802.11 standards (often described as wireless LAN or Wi-Fi) provide high data rate wireless access over short distances that enable the deployment of hotspot networks (where base stations are located in numerous amenities such as cafes, libraries or universities) or mesh networks. 802.11b, or Wi-Fi, is a standard for wireless LANs operating in the 2.4 GHz spectrum with a data rate of up to 11 Mbit/s, while 802.11a is a standard for WLANs operating in the 5 GHz frequency range with a maximum data rate of 54 Mbit/s. The 802.11g standard is for WLANs operating in the 2.4 GHz frequency, but with a maximum data rate of 54 Mbit/s.
The relatively low cost of 802.11 base station and mesh network infrastructure coupled with the use of class-licensed spectrum enables the deployment of networks covering significant portions of metropolitan and some regional areas and it allows the service to become portable despite its short ranges.
The 802.16 standard (also known as WiMAX) specifies fixed point-to-multipoint broadband wireless systems operating in the 10–66 GHz licensed spectrum. An amendment, 802.16a, specifies non line-of-sight extensions in the 2–11 GHz spectrum, delivering data rates of up to 70 Mbit/s at distances up to 50 kilometres.
These standards offer fixed wireless access with the possibility of portability. The IEEE 80.16 Working Group is developing the 802.16e that may offer similar performance attributes combined with mobility.
As the name suggests, internet access is provided via satellites which orbit the earth at a fixed point along the equator. It is an access technology often used as an alternative to having fixed lines installed to remote premises. Satellite services in Australia offer 2-way services, meaning that the satellite transmission is used for both downloading and uploading. 1-way services use satellite for download, but use a fixed line (often ISDN) for uploading data. The Australian market currently offers plans with download data rates of 256 kbit/s to 800 kbit/s.
Advertised data rates (which is the line data rate between the customer and the ISP) cannot be considered as the expected throughput benchmark because they only indicate the maximum achievable data rates. As such, internet access plans are often advertised with the words ‘achieve data rates of up to’ 256 kbit/s, for example. Advertised data rates for internet services are used to enable consumers to compare service offerings. Actual data rates are unlikely to be exactly as advertised because of technological and environmental factors. Some of these factors are discussed below.
The theoretical download data rate for most dial-up internet connection is 56 kbit/s. This speed can be expected on a dedicated twisted copper pair that is close to a telephone exchange, however, this speed may not be achieved due to other factors. As the previous sentence suggests, the further the end-user is from the exchange much of the signal transmitted along the line is attenuated (diminished) without loading coils that regenerate the signal. Similar principles apply ISDN and ADSL.
With older ‘pair gains’ systems which share copper twisted wiring among multiple users, data rates are often impeded and simultaneous access to all end-users is not achievable. Under government direction Telstra is currently reducing the number of old pair gains systems.
ADSL technology uses existing telephone infrastructure (twisted copper wiring) where in most cases there is a dedicated line between the end-user and the telephone exchange. In some cases there is no dedicated line to individual end-users. In some locations (especially in regional areas) there are network configurations where end-users are connected (by copper pairs) to Remote Integrated Multiplexers (RIMs), which is in turn connected (by optical fibre) to the exchange. This network configuration often prohibits (for certain technical and commercial reasons) the provision of ADSL services to end-users. Telstra has a demand register where they track consumer requests for RIMs to be upgraded to support ADSL. For further information, please contact Telstra.
Pair gains systems may also prohibit end-users from accessing ADSL. As mentioned above, Telstra is continuing to upgrade old pair gains systems to support ADSL services. Distance from the exchange also has a large bearing on the ability of some consumers to access ADSL due to technical limitations. Consumers should check availability with their service providers.
Hybrid Fibre Coaxial (HFC) Cable
ADSL technology uses existing telephone infrastructure where in most cases there is a dedicated line between the end-user and the telephone exchange. In contrast, HFC networks are engineered in such a way that end-users have shared infrastructure before reaching the exchange. Consequently, if there are many users on a shared HFC backbone at any one time, congestion may occur and data rates may decrease.
Wireless internet services do not have a dedicated transmission pathway (for last mile access) as do cable or twisted copper lines. Since wireless last mile access is transmitted through the atmosphere and the condition of the atmosphere is variable, variability in service performance is also expected. Impediments to optimum wireless service include poor radio conditions in the atmosphere and local interference from other devices using similar frequency bands.
Some wireless technology such as microwave links require ‘line of sight’ between transmitters and receivers. ‘Shadows’ occur when objects and landscapes such as hills obstruct the line of sight which can impede or completely obstruct data transmission.
For nomadic or mobile wireless access, the speed at which an end user is moving may also affect the data rates.
Satellite service may vary due to a number of factors. Attenuation and noise are likely to occur during the thousands of kilometres that satellite signals need to travel. Performance generally varies the further away a service is from the satellite. In the case of geosynchronous satellites (which are maintained above the equator) satellite dishes in Southern Australia will receive weaker signals that dishes in Northern Australia. Poor conditions in the atmosphere, for example heavy rainfall, smoke/fog/smog, dust, and water vapour may hinder signal transmission.
Services may also be hindered if the satellite dish is not properly aligned.