The "last mile" is the final leg for delivering internet connectivity to a customer. The technology employed for that last mile is dependent on the Internet Service Provider and/or on the terrain and remoteness of the customer.  The technology may be either wired or wireless.

Wired systems include the copper telephone line using ADSL or VDSL modems, coaxial cable or fibre optic cable.  To achieve the government's objective data speeds, ADSL and VDSL connections are limited to about 2km of an access point (a school, telephone exchange or 'telecom cabinet').  Coaxial cables (referred to as a 'Cable' connection) are available only in the major cities.  Fibre optic cables offer the fastest data speeds and are future proof against changes in technology.

Wireless systems include satellite; mobile broadband (Telecom XT and Vodafone 3G netwroks); WiMax (Worldwide Interoperability for Microwave Access), which is a broadcast radio technology serving a wide geographical area; and point to point radio systems.

The information below is provided by Wikipedia and the full text can be viewed at http://en.wikipedia.org/wiki/Last_mile

Wired systems (including optical fiber)

Wired systems provide guided conduits for Information-Carrying Energy (ICE). They all have some degree of shielding which limits the susceptibility to external noise sources. These transmission lines have losses which are proportional to length. Without the addition of periodic amplification, there is some maximum length beyond which all of these systems fail to deliver adequate S/N to support information flow. Dielectric optical fiber systems support heavier flow, at higher cost.

Local area networks (LAN)

Traditional wired local area networking systems require copper coaxial cable or twisted pair to be run between or among two or more of the nodes in the network. Common systems operate at 100 Mbit/s and newer ones also support 1000 Mbit/s or more. While the maximum length may be limited by collision detection and avoidance requirements, signal loss and reflections over these lines also set a maximum distance. The decrease in information capacity made available to an individual user is roughly proportional to the number of users sharing a LAN.

Telephone

In the late 20th century, improvements in the use of existing copper telephone lines increased their capabilities if maximum line length is controlled. With support for higher transmission bandwidth and improved modulation, these digital subscriber line schemes have increased capability 20-50 times as compared to the previous voiceband systems. These methods are not based on altering the fundamental physical properties and limitations of the medium which, apart from the introduction of twisted pairs, are no different today than when the first telephone exchange was opened in 1877 by the Bell Telephone Company. The history and long life of copper-based communications infrastructure is both a testament to our ability to derive new value from simple concepts through technological innovation – and a warning that copper communications infrastructure is beginning to offer diminishing returns on continued investment.^[1]

Optical fiber

Fiber offers high information capacity and more recently is becoming the deployed medium of choice given its scalability in the face of increasing bandwidth requirements of modern applications.

In 2004, according to Richard Lynch, EVP and CTO of telecom giant Verizon, they saw the world moving toward vastly higher bandwidth applications as consumers loved everything broadband had to offer, and eagerly devoured as much as they could get, including two-way, user-generated content. Copper and coaxial networks wouldn’t – in fact, couldn’t – satisfy these demands, which precipitated Verizon's agressive move into Fiber-to-the-home via FIOS. ^[2]

Fiber is a future-proof technology that meets the needs of today's users, but unlike other copper-based and wireless last-mile mediums, also has the capacity for years to come, by upgrading the end-point optics and electronics, without changing the fiber infrastructure. The fiber itself is installed on existing pole or conduit infrastructure and most of the cost is in labor, providing good regional economic stimulus in the deployment phase and providing a critical foundation for future regional commerce.

Wireless delivery systems

Mobile CDN coined the term the 'mobile mile' to categorize the last mile connection when a wireless systems is used to reach the customer. In contrast to wired delivery systems, wireless systems use unguided waves to transmit ICE. They all tend to be unshielded and have a greater degree of susceptibility to unwanted signal and noise sources. Because these waves are not guided but diverge, in free space these systems have attenuation which is inversely proportional to distance squared. Losses thus increase more slowly with increasing length than for wired systems whose loss increases exponentially. In a free space environment, beyond some length, the losses in a wireless system are less than those in a wired system. In practice, the presence of atmosphere, and especially obstructions caused by terrain, buildings and foliage can greatly increase the loss above the free space value. Reflection, refraction and diffraction of these waves can also alter their transmission characteristics and require specialized systems to accommodate the accompanying distortions.

Wireless systems have an advantage over wired systems in last mile applications in not requiring lines to be installed. However, they also have a disadvantage that their unguided nature makes them more susceptible to unwanted noise and signals. Spectral reuse can therefore be limited.

Lightwaves and free-space optics

Visible and infrared light waves are much shorter than radio frequency waves. Their use to transmit data is referred to as free-space optical communication. Being short, light waves can be focused or collimated with a small lens/antenna and to a much higher degree than radio waves. Thus, a greater portion of the transmitted signal can be recovered by a receiving device. Also because of the high frequency, a high data transfer rate may be available. However, in practical last mile environments, obstructions and de-steering of these beams, and absorption by elements of the atmosphere including fog and rain, particularly over longer paths, can greatly restrict their use for last-mile wireless communications. Longer (redder) waves suffer less obstruction but may carry lesser data rates. See RONJA.

Radio waves

Radio frequencies (RF), from low frequencies through the microwave region, have wavelengths much longer than visible light. Although this means that it is not possible to focus the beams nearly as tightly as for light, it also means that the aperture or "capture area" of even the simplest, omni-directional antenna is greatly larger than that of a lens in any feasible optical system. This characteristic results in greatly increased attenuation or "path loss" for systems that are not highly directional. In actuality, the term path loss is something of a misnomer because no energy is actually lost on a free-space path. Rather, it is merely not received by the receiving antenna. The apparent reduction in transmission, as frequency is increased, is actually an artifact of the change in the aperture of a given type of antenna.

Relative to the last-mile problem, these longer wavelengths have an advantage over light waves when omni-directional or sectored transmissions are considered. The larger aperture of radio antennas results in much greater signal levels for a given path length and therefore higher information capacity. On the other hand, the lower carrier frequencies are not able to support the high information bandwidths which are required by Shannon's equation, when the practical limits of S/N have been reached.

For the above reasons, wireless radio systems have the advantage of being optimal for lower-information-capacity broadcast communications delivered over longer paths. For high-information capacity, highly-directive point-to-point over short ranges, wireless light-wave systems are most useful.

One-way (broadcast) radio and television communications

Historically, most high-information-capacity broadcast has used lower frequencies, generally no higher than the UHF television region, with television itself being a prime example. Terrestrial television has generally been limited to the region above 50 MHz where sufficient information bandwidth is available, and below 1000 MHz, due to problems associated with increased path loss as mentioned above.

Two-way wireless communications

Two-way communication systems have primarily been limited to lower-information-capacity applications, such as audio, facsimile. or radio teletype. For the most part, higher-capacity systems, such as two-way video communications or terrestrial microwave telephone and data trunks, have been limited and confined to UHF or microwave and to point-point paths. Higher capacity systems such as third-generation, 3G, cellular telephone systems require a large infrastructure of more closely spaced cell sites in order to maintain communications within typical environments, where path losses are much greater than in free space and which also require omni-directional access by the users.

Satellite communications

For information delivery to end-users, satellite systems, by nature, have relatively long path lengths, even for low earth-orbiting satellites. They are also very expensive to deploy and therefore each satellite must serve many users. Additionally, the very long paths of geostationary satellites cause information latency that makes many real-time applications unusable. As a solution to the last-mile problem, satellite systems have application and sharing limitations. The ICE which they transmit must be spread over a relatively large geographical area. This causes the received signal to be relatively small, unless very large or directional terrestrial antennas are used. A parallel problem exists when a satellite is receiving. In that case, the satellite system must have a very great information capacity in order to accommodate a multitude of sharing users and each user must have large antenna size, with attendant directivity and pointing requirements, in order to obtain even modest information-rate transfer. These requirements render high-information-capacity, bi-directional information systems uneconomical. This is a reason that the Iridium satellite system was not more successful.

Broadcast versus point-to-point

For both terrestrial and satellite systems, economical, high-capacity, last-mile communications requires point-to-point transmission systems. Except for extremely small geographic areas, broadcast systems are only able to deliver large amounts of S/N at low frequencies where there is not sufficient spectrum to support the large information capacity needed by a large number of users. Although complete "flooding" of a region can be accomplished, such systems have the fundamental characteristic that most of the radiated ICE never reaches a user and is wasted. As information requirements increase, broadcast "wireless mesh" systems (also sometimes referred to as microcells or nano-cells) which are small enough to provide adequate information distribution to and from a relatively small number of local users, require a prohibitively large number of broadcast locations or "points of presence" along with a large amount of excess capacity to make up for the wasted energy.