4 THE FUTURE FOR HANDHELD TECHNOLOGY
4.3 Future Generations of Mobile Communications: 3G, 4G, 5G…
Future mobile communication technological advance is one of the core drivers for more enabled mobile Handheld devices. Until these services are global and provided at a reasonable cost to the user, most of the other future technologies identified will not be feasible for mobile Handheld devices. The transitional generation service from 2G to 3G, 2.5G or GPRS, is widely available at current. The 3G services such as UMTS, WCDMA, and EDGE are currently available at limited locations around the world and on limited devices.
The following section looks at some of the technologies which will enable future generation mobile communications.
Ohmori et al (2000) identified the following enabling technologies to provide for future generation mobile communication systems:
• Modulation and Signal Transmission- refers to robust modulation demodulation schemes to withstand frequency-selective fading;
• Propogation- refers to improvements in mobile propagation characteristics of microwaves;
• Software Radio- refers to coexistence of several mobile telecommunication services;
• Smart Antennas- refers to intelligent functions such as suppressions of interference signals, auto tracking of desired signals, and digital beamforming with adaptive space- time processing technologies for future mobile communications;
• Radio on Fibre- refers to transmitting radio signals through optical fibres;
• Network Architecture and Protocol- refers to air interface protocol suitable for IP packet transmission, location registration, and base station network configuration, wireless QoS control, network configuration that facilitates the introduction of the microcells, and integrated seamless service control with 3G cellular and wireless LANs; and
• Devices- refers to important components in high-frequency systems such as high- efficiency power amplifiers, ultra-low-temperature compact receiver amplifiers, and antennas.
Ohmori et al (2000) also discussed the various candidates for future generation communication systems. These include:
• 4G-Cellular Systems- This is involves three layers-
o the physical network providing access and routing functions in an integrated format for both radio and core networks;
o the middleware environment acts as a bridge between the application and physical network and provides functions such as QoS mapping, address conversion, plug and play, security management, and an active network; and o The application environment is an open interface enabling third parties to
develop and provide new applications and services easily.
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• Broadband Wireless Access and Local Area Networks
The Japanese started working on a 4G system of this type in 1996. They called it the Multimedia Mobile Access Communication (MMAC) System. It is slated to be available after the 3G IMT-2000 network. The MMAC promises to provide two categories of high speed wireless access communications. The first will transmit up to 30 Mbps using 5.2 GHz and service both indoors and outdoors. The second will provide ultra-high speed WLANs indoors, which can transmit high-speed signals up to 600 Mbps using the millimetre-wave radio band (e.g. 60 GHz). Prototype millimetre-wave wireless LANs have been developed to demonstrate feasibility of 60 GHz WLAN systems with asynchrononous transfer mode (ATM) or 100-base Ethernet interfaces operating at data rates up to 155 Mbps.
• High Altitude Stratospheric Platform Station Systems
The High Altitude Stratospheric Platform Station System (HAPS) involves a platform at approximately 20 km high in the stratosphere creating a mesh like network through optical intercommunication links. A broadband access link is the link between the platform station and the user station. The anticipated frequency band of the access link is expected to be millimetre-wave band. The expected bit rate of the access link is 25 Mbps for most fixed and portable terminals to 200 Mbps for limited fixed terminals with antennas larger than standard.
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Gazis et al (2002) investigated 4G mobile communication systems with a view to proposing a set of priorities for a research agenda. They commented that the widely accepted vision for 4G includes “a heterogeneous communication landscape comprising different wireless access systems in a complementary manner where the user, supported by his/her personal intelligent agent (s), enjoys untethered connectivity and ubiquitous access to applications over the most efficient combination of wireless systems available”. Furthermore, they predicted that future mobile communication systems will be “heterogeneous in nature, forming an integrated network environment that comprises various wireless technologies and
access systems in a complementary manner”. They expect that wireless access networks, regardless of their internal technical details, to have the following in common (Gazis et al, 2002):
• A dynamic address assignment mechanism (e.g., DHCP, SLP, GPRS/UMTS) that is capable of associating a short-lived or long-lived IP address to the respective wireless interface at the mobile terminal.
• A transparent IP forwarding service that is accessible over the logical termination of the IP layer at the mobile terminal and one or more gateways (e.g., GGSN, Mobile IP- aware router) at the wireless access network infrastructure. The IP forwarding service is established by employing signalling procedures (e.g., PDP context signalling in the UMTS case) specific to the technical architecture of each wireless access network.
Technology-agnostic API Traffic Flow Objects
Technology-dependent objects Applications
Virtual Machine
Transport Services QoS Manager
UDP RTP
TCP RSVP
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The future generation of mobile communication technologies will enable greater functionality for Internet applications. Experts are already talking about the new Internet or Xnet. The X Internet will allow the user’s computer to receive mini-programs that manipulate the information sent along with it so it can be customised for the device it’s being sent to. This
will allow other users to get access to what has been done and have the benefit of whatever modifications or improvements made (Axelrod, 2001).