4G - 4th Generation Mobile Communication Networks

Elias Abboud (00041172), Dinesh Gurram (00053746), James Pearce (00059345)

Research Assignment
Communication Networks 48740
University of Technology, Sydney


Statement of Originality

The work contained in this assignment, other than that specifically attributed to another source, is that of the author(s). It is recognised that, should this decleration be found to be false, disciplinary action could be taken and the assignments of all students involved will be given zero marks.


 

Contents

Key Learning Points

Introduction
      Why 4G?
      What is 4G?
      Charcteristics of 4G
            Fully Converged Services
            Ubiquitous Mobile Access
            Software Dependency
            Diverse User Devices
            Autonomous Networks
            4G Services

Evolution of 4G
      Past and Present Generations
            1G
            2G
     
3G: The Next Step Forward
      3G to 4G

4G Architecture and Operation
      4G Core Network
            Requirements
            Characteristics

      Location Management
      Coverage
            Spectrum Requirements
            Coverage

      Hand-over
      Movable Networks
      Mobility Control
      Wireless LAN Integration
      HIPER LAN 2
      BlueTooth
            BlueTooth Specifications
            5 Layers of Wireless Communications

Non-technical Factors
      Social Implications
      Economic Implications
      Health Isssues

Conclusion

Glossary

Multiple Choice Review Questions
      Questions
      Answers

References

 

Key Learning Points

  • Mobile communications trends show that in the future the public's requirements will outgrow the services offered by 3G (3rd Generation Mobile Systems), and a majority of the traffic will be data and multimedia as opposed to voice only.

  • 4G is the evolution of 3G to meet the forecasted rising demand. It is an improvement on, and an integration of various existing technologies including GSM, GPRS, CDMAone, IMT-2000, Wireless LANs and BlueTooth. Thus full backward compatibility is maintained. Data rates in 4G systems will range from 20 to 100 Mbps.

  • As 3G is only just beginning to be implemented, the transition to 4G will most likely be gradual and changes will be made in phases. Much of the 2.5G and 3G infrastructure will be relied upon as a foundation for 4G.

  • The 4G architecture will build upon 3G. Certain components such as the circuit-switching elements are removed and Wireless LAN connectivity is added. The IP Core network has much more stringent requirements and is developed further to support high data rates, provide advanced application services support and manage itself as well as the radio network more efficiently.

  • 4G cellular services will have to operate at higher frequency bands than 3G to achieve high data rates. There are many resulting complications to be addressed. Mobility control, Location management, Hand-overs, etc have to be performed more efficiently in 4G.

  • While various technological issues are addressed we also have to look at the consequences of these developments in terms of social, economic and health implications and bear in mind how 4G will affect the entire society.
  •  

    Introduction

    4G (short for 4th Generation Communication Systems) represents the future of mobile communications in the longer term.

    Currently we are using and experiencing mainly 2G (2nd Generation) technology. To be accurate, we are at a stage when 2G is giving way to the succeeding generations - 2.5G (enhancements on 2G) and 3G (3rd Generation) technologies. While 2.5G has been available for the past couple of years 3G is only just beginning to be rolled out in many countries. It is expected to be fully deployed on a worldwide scale by 2005.

    With each generation a gradual evolution and improvement of technology has occurred. The standardisation process has also become more streamlined with each generation.


    Why 4G?

    This raises the question, if 3G is not quite established yet, why are we talking about 4G? The answer is that if research and planning into 4G is not carried out now, it will not be possible to keep up with consumer demand. While 3G will attempt to satisfy demand in the current and short-term future, the market will outgrow 3G in a matter of years. The importance of planning ahead to 4G is also highlighted by the fact that 3G Systems are not cross-compatible or unified on a worldwide scale and may not live up to all the hype.

    With mobile communications, the evolutionary pattern seems to follow 1-decade cycles. In the 80's it was 1G, in the 90's 2G and now in the new century 3G systems are being introduced. Thus it seems logical that 4G will be introduced around the 2010 mark.

    In the US, in the period between 1994 and 2001 mobile phone subscribership increased from 16 million to 110 million. Such trends have been witnessed in most developed and various developing nations. In Japan, the 'i-mode' mobile Internet service already had approximately 17 million subscribers by the end of 2000. This figure doubled by mid 2001.


        Predicted trends in mobile communications (Source: 10)

    These statistics and trends indicate that while the number if subscribers to mobile services increase steadily, the requirements of a mobile communication system will also change. In the past the mobile phone has been used mainly for voice application and person-to-person contact. In the future the demand will shift towards data and multimedia services rather than voice. According to estimates, in 2005, of the 1.6 billion Internet users worldwide, 1 billion will be mobile Internet users, and by 2015 mobile traffic is expected to grow to 23-fold that of today, with 90 % being multimedia.


    What is 4G?

    4G is an attempt to evolve, integrate and amalgamate the current 2G (2nd Generation), the soon to be released 3G (3rd Generation), broadcast, WLAN (Wireless Local Area Network), short-range and fixed wire systems into a single, fully functional, seamless internetwork.

    4G is NOT a complete overhaul of all old technology. It involves a mix of current concepts and technologies in the making. Some of these are derived from 3G and hence are evolutionary, while others are totally new concepts and can be thought of as revolutionary.

    4G will feature a scalable, flexible, efficient, autonomous, secure and feature-rich backbone to support a multitude of existing and new services and to interface with many different types of networks. It will offer fully converged services (voice, data, and multimedia) at data rates of up to 100 Mbps and ubiquitous mobile access to a vast array of user devices autonomous networks.


    Characteristics of 4G

    Fully Converged Services

    A wide range of services will be available to the mobile user conveniently and securely via the 4G Core Network. Personal communications, information systems and entertainment will seem to be merged into a seamless pool of content.

    Ubiquitous Mobile Access

    4G aims to provide access to multimedia services anytime anywhere. Devices will not simply rely on cellular reception. Improved radio access technology as well as integration of all types of communication networks allows for virtually constant connectivity to the 4G core backbone. Mobile handsets will be intelligent and software-reconfigurable on the fly to allow them to interface with different types of networks on the move. Also, there will be full cross compatibility on a world-wide scale since each type of network has a gateway to the IP backbone.

    Software Dependency

    Advanced software systems are employed for all purposes - network operation, service provision, interfacing and integration, etc. Not only the Core Network but the mobile devices will be highly intelligent as well as re-configurable via software.

    Diverse User Devices

    A defining feature of 4G will be the proliferation of a vast array of devices that are capable of accessing the 4G backbone. Wireless capabilities will be embedded into devices that we wouldn't even consider today. Not only personal devices like phones, PDAs, laptops, etc. but also sensors, embedded controllers and other specialised equipment. The point behind this is to allow them to autonomously communicate with each other. By building in sophisticated software, they will be able to automatically initiate timely actions. 2G enabled mobile person-to-person communications while 3G is opening the door to person-to-machine communication with mobile Internet. 4G introduces another dimension with machine-to-machine communication.

    Autonomous Networks

    While user devices are highly intelligent, the core network will also be very sophisticated. It will be capable of managing itself and dynamically adapting to changing network conditions and user preferences for seamless communication. Apart from evolved mobility management, connection control, hand-over mechanisms, etc, dynamic bandwidth allocation will make far more efficient use of the available radio spectrum.

    4G Services

    4G data rates will between a few Mbps and 100 Mbps, hence the level of service that can be offered is quite tremendous. Apart from 3G services like World Wide Web, Email, and wireless E-commerce this data rate is quite adequate to support the high QoS levels required for high-resolution multimedia traffic. Broadcast services will most likely become on-demand infotainment services. Video-conferencing services will be of high quality and almost as good as meeting in person. Ad Hoc networking (dynamic formation of wireless networks between wireless devices without any central infrastructure or administration) will allow for Personal Area Networks, in-house networks and the like which allow wireless devices to perform various activities autonomously. Alarm notification, sensor data acquisition and remote control of home appliances are some of the possibilities. It is more than likely that mobile services that have not even been envisaged will exist in 4G.

     

    Evolution of 4G

    Past and Present Generations

    1G

    Commercial mobile communications systems first appeared in the early 1980's (1G). These systems were based on analogue transmission and a relatively small proportion of the population had access to these systems. Some flaws with these systems were that they did not provide a great deal of security and standardisation was not controlled particularly well.

    2G

    The first 2G systems were standardised and deployed in the early 90's. The GSM (Global System Mobile) standard has come to dominate but other co-existing technologies also operate such as CDMAone.
    GSM uses TDMA (Time Division Multiple Access) in which each cellular channel is divided into a number of time-slots that are shared amongst a group of callers within a cell.
    CDMAone, on the other hand, employs CDMA (Code Division Multiple Access) in which multiplexing is done on the basis of special mathematical codes used to encode the signal from each phone.

    2G systems were developed primarily for voice communications and incorporated circuit-switching technology. In the past decade, some data capability has been added on with SMS (Short Message Service) and WAP (Wireless Application Protocol) but these are quite limited in terms of functionality and available capacity. GSM can offer a maximum of 9.6 Kbps per channel which is sufficient for voice but not suitable for any substantial data traffic.

    In a GSM network mobile phones are in constant contact with the nearest BTS (Base Terrestrial Station) which is connected to a BSC (Base Station Controller) along with several other BTSs). The network of BSCs reports to a MSC (Master Station Controller) which manages the communications. It performs a number of functions including mobility management, authentication, encryption, billing, connectivity to PSTN (Public Switched Telephone System), etc.

    In recent years some other enhancements have also been installed to allow GSM networks to handle packet-switched data. GPRS (General Packet Radio Service) for example, involves the addition of a PCU (Packet Control Unit) at each BSC and an IP (Internet Protocol) based core network to which packet-switched data from the PCU is routed. In this architecture circuit-switched traffic is still handled by the MSC whereas the equivalent function for packet-switched data is performed by a SGSN (Supporting GPRS Support Node). The GGSN (Gateway GPRS Support Node) provides a gateway from the IP backbone to other networks such as Enterprise Intranets or the public Internet.

    GPRS allows for a GSM channel to be divided into 8 streams of 13 KBps each and for concurrent transmission of packets along each to yield a maximum of around 100 KBps. Another feature of GPRS is that it allows for simultaneous data transfer and voice calls. Because of the packet-switched nature of the mobile Internet services to GPRS phones charging is on the basis of how much data is transferred rather than how long the phone is connected to the Internet (as with WAP over circuit-switched GSM). As this applied to any packet-switching approach prices for data services in GPRS and beyond are significantly reduced, and also, constant connectivity to the IP-backbone is also made possible.

    The public interest in GPRS has not been particularly enthusiastic, the reason being that it has not lived up the expectations. Actual speeds have been considerably lower than the 100 KBps mark. EDGE (Enhanced Data Rates for GPRS Evolution) is an attempt to improve data rates and deliver up to 384 Kbps. It represents another step towards 3G. In some respects EDGE itself can be considered a 3G technology and some operators may choose to skip this step and implement the IMT-2000 3G standard.


    3G: The Next Step Forward


        Evolution Path to 3G (Source: 17)

    3rd Generation systems are beginning to be deployed in many countries. 3G extends mobile services to include multi-rate multimedia content. The inter-connection between the wired Internet and the cellular world is firmly established with 3G. The IMT-2000 (International Mobile Telecommunications System 2000) encompasses the standards that 3G systems will be based upon. The standards use one of two technologies - W-CDMA (Wideband CDMA) or CDMA-2000. UMTS (which is likely to dominate as GSM has) will employ W-CDMA. Although there is a genuine attempt to unify IMT-2000 totally, 3G will not be cross-compatible on a world-wide scale which means that world-wide roaming is not 100% feasible across all carrier networks.

    There is not a great deal of difference between the two and as the names suggest, they are both more advanced, higher-speed variants of CDMA technology. The choice between the two is essentially determined by the pre-existing infrastructure. In general, GSM and GPRS networks are most likely to migrate to UMTS and CDMAone networks are most likely to move to CDMA-2000.

    3G will provide a potential maximum of 2 Mbps. It is predicted however, that such high rates will only be available at zero or very low pace and in close range from the BS (Base Station - the 3G version of a BTS). However, there is certainly a marked improvement over GPRS as the minimum data rate is expected to be around 144 Kbps. Furthermore, 3G offers different capacity services at different QoS levels.

    An improved radio air interface standard in 3G supports high spectral efficiency and higher frequency bands (2 GHz band) with greater bandwidths are also utilised to achieve the higher data rates.

    In the UMTS 3G architecture the UTRAN (UMTS Terrestrial Radio Access Network) is a hierarchical network comprising of RNCs (Radio Network Controllers) and BSs. Since backward compatibility is maintained in 3G the BTS is simply augmented to incorporate the BS.

    The RNC takes the place of the BSC but it has a greater role to play. As it is interconnected with other RNCs it provides local hand-over and some call-control between cells that fall under these RNCs in the hierarchy. This decentralises some of the MSC functionality freeing up MSC resources. The RNC also connects directly to the 3G SGSN.

    The BS also has a more evolved role. Soft Hand-over, or Diversity Hand-over is a particularly useful inheritance from CDMAone. In this scheme, when a MT (Mobile Terminal) can reach more than one BS (eg. at a cell boundary) the uplink signal reaches the RNC through both BSs. The RNC uses sophisticated signal handling to combine them into a single data stream. This improves signal quality and provides a more seamless service.


    3G to 4G

    A basic comparison of 3G and 4G:

    3G
    4G
  • Data Rates of 100 Kbps to 2 Mbps


  • Goal is 'to provide multimedia multirate mobile communications anytime and anywhere'.


  • Connection between the cellular world and the wired Internet firmly established.


  • Mobile devices used mainly for Human-to-Human and Human-to-Machine communication.


    • Data Rates up to 100 Mbps
    • Expansion on the 3G goal to provide a wider range of new and improved multimedia services.
    • Integration of broadcast, cellular, cordless, Wireless LAN, short-range and fixed wire systems to appear as a single seamless network.


    • Not only the 3G modes of communication but also characterized by a great deal of Machine-to-Machine traffic

    Apart from the differences mentioned above, 4G also aims to:

  • Develop the IMT-2000 CDMA technologies to make more efficient use of the available frequency spectrum.
  • Evolve the Cellular Network Architecture to suit high levels of mobility and purely packet-switched data.
  • Allow for short-range Ad Hoc networking among wireless devices.
  • Make significant advances on the security and scalability of 3G

      • Evolution Path to 4G (Source: 10)

     

    4G Arhitecture and Operation

    The architecture of the 4G network will more or less resemble the 3G architecture but there are some significant evolutionary changes. Circuit-switching capabilities are redundant in 4G and are thus removed. The MSC used previously to service legacy 2G voice traffic is discarded and all voice traffic is treated as packet data at the BS. Backward compatibility is maintained by segmenting voice data into packets and routing them through the IP backbone using VOIP (Voice Over IP) technology. A VOIP Gateway is used to connect to PSTN or ISDN.

    Another major advancement that 4G makes is the integration of Wireless LANs into the total mobile network. The situation will be similar to what is happening today with wired LANs - the line between a wired WAN and a wired LAN has blurred with the use of same technologies in both (eg. ATM). Similarly, new air interface standards are being developed for high-speed wireless LANs in conjunction with those for the cellular 4G network, which will allow wireless LANs to be interconnected to the 4G IP backbone simply via routers with wireless access built-in.

    A related concept is Ad Hoc Networking. This concept refers to the formation of wireless LANs on an ad hoc basis. In other words, a group of wireless devices will be able to create or join a wireless network without any central infrastructure or administration. All interfaces are air interfaces in this scheme and there is no need for a CM (Control Module) connected to any wired infrastructure. 4G will support ad hoc networking via a more evolved version of a currently existing standard called BlueTooth. Ad hoc networking is particularly important step because it allows for the development of a wide range of different devices which will be able to autonomously communicate with each other within a short-range even when they don't have complete cellular access capabilities.

     

    The 4G Core Network

    Requirements

    The requirements of a 4G core network are:

      1. The ability to handle a very high level of multimedia traffic.
      2. Advanced mobility management (this involves location management and managing hand-overs)
      3. Diversified radio access support (this refers to support for features like various QoS levels and transmission speeds, independent uplink and downlink capacity).
      4. Seamless service: the delivery of data must be smooth and not be affected by any transitions in the user's situation:
        -Network-seamless
        -Terminal-seamless
        -Content-seamless
      5. Support for a diverse range of applications - i.e support structure for wireless ASPs (Application Service Providers), who are third-party providers of high-level services similar to ASPs in the wired Internet today).

    Characteristics

    The IP core network will be based on IPv6 (IP Version 6) instead of IPv4. This is more conducive to a large number of devices with IP addresses and also supports mobility far better than its predecessor. The IP core will most likely be implemented using ATM (Asynchronous Transfer Mode) - an evolutionary step from the Frame Relay based 3G core.

    The Core network may be viewed as consisting of 3 layers - the Transport Network, the Service Middleware and the Applications. The Transport Network is the actual network interconnection and will be configured by routers, as with any IP network.

    The Service Middleware is at the hardware and software level (hence the name, middleware). This will be implemented in Servers running specialised software. On one side, this will provide application support with such functions as billing, media conversion, location registration, billing and so on. Known as the Service Support Layer this also provides an API (Application Programming Interface) through protocols such as JAIN and Parlay which are in the process of being standardised. On the other side, the Service Middleware will perform network and transport management with functions like RRM (Radio Resource Management), MM (Mobility Management), C/SM (Call and Session Management), etc.

    The Core Network is inherently network-seamless since it is based on IP, the most universal Network layer protocol. Also, nodes can be configured to allow connectivity with other types of networks. The Service Middleware provides the content-seamless and terminal-seamless service. Location Management keeps track of the whereabouts of any mobile device and its movement characteristics. Thus, media conversion can take place when necessary according to the user's current situation and preferences. For example, the video resolution may be automatically reduced when user changes from a large-screen terminal (stationary location) to a smaller screen (on the move). Another example is the conversion from real-time video to audio when the user has to drive a vehicle.


        Layered view of the IP-based Core Network in 4G (Source: 2)

     

    Location Management

    In 2G and 3G systems Location Management is done for individual MTs. Each device registers its current location with the Core Network whenever it crosses the border of a location registration area. This leads to a wasteful signaling load because there are several occasions when the location of each MT in a group is not independent (eg. a train full of people with mobile devices).

    4G will allow for Concatenated Location Registration. If the movement characteristics of a group of MTs are more or less similar their location registrations are concatenated, provided there is a common entity to concatenate with. Using the train example, assuming that the train itself performs location registration, a MT boarding the train only has to report to the Core Network that it is concatenated to the train. For the duration of the trip the Core network can perform location management based on the train's registration information. Considering the number of MT devices that can be on the train at one time, the signaling load is considerably less than if each device performed separate location registration every time the train crosses a cell edge. This will also help in cutting out any jitter or latency that may occur at cell boundaries in the hand-over process delivering a more seamless service.

     

    Coverage

    Spectrum Requirements

    However efficiently the frequency spectrum is utilised the maximum achievable channel capacity over a given bandwidth B is limited by the Nyquist Bandwidth formula, given by:

      C = 2B * log2M
      Where C = Channel Capacity, M = number of discrete signaling levels

    The value of C for 3G systems is less than the minimum value of 20 Mbps for 4G communications. Hence, it is inevitable that higher frequency bands will have higher frequency bands will have to be used in order to use a wider bandwidth in order to achieve the high data rates. This is not a simple task however, because the frequency band has an effect on the cell-sizes that 4G can accommodate.

    Coverage

    4G will provide varied service quality according to distance from dense urban areas. Data rates in rural areas are expected to be lower than those enjoyed in dense urban areas. In the most likely case 4G coverage will extend to metropolitan areas and 3G systems will be utilised beyond them. The reason is partly economical, but cell-sizes also play a role in this.

    The 4G cell radius will, in general, most likely be smaller because the propagation loss is increased by operating at higher frequencies and at higher transmission bit rates the received signal level threshold must be higher than at lower bit rates, in order to compensate for the greater affect of noise at higher bit rates (i.e to receive the signal at an adequate SNR).

    The Equations that govern cell size:

      Lp = 38 * log(d) + 21 * log(f) + c
      dLb = 10 * log(B/B0)
      Rr = 1/10 ^ ( (21 * log(f/f0) + 10 * log(B/B0)) / 38 )
      Where:
      Lp = Propagation Loss, d = Distance, f = frequency
      c = constant, dLb = Increase in noise power, B = Bit rate,
      B0 = Reference Bit Rate, Rr = Relative Cell Radius,
      f0 = Reference frequency

    Greater bit rates as well as higher frequency bands both result in smaller cell size. A cell-size decrease by half will result in 4 times the number of BSs being required to cover the same area. This is a very important consideration because laying down infrastructure incurs the greatest cost to the network providers. Another consequence of this is that cell sojourn time (average time spent within a cell) is reduced and hand-over frequency is increased.

     

    Hand-over

    Due to the increased hand-over frequency the load on RNC signal processing equipment is also increased greatly. This is detrimental to system performance and seamless service. At such high data rates the hand-over process must be as quick and efficient as possible.

    A change in the RAN (Radio Access Network) architecture can provide a solution to thia. Instead of forming a 'Star' structure with BSs the RNC forms a 'Ring' known as a Cluster. The RNC also acts as a BS. It becomes the 'Cluster Head'. Diversity Hand-over is carried out in a distributed manner within the cluster. The uplink signal received by multiple BSs is passed onto one of the BSs which acts as a 'Temporal Agent'. The dynamically assigned Temporal Agent performs the signal processing previously handled singularly by RNC. The processed signal is sent to the Cluster Head to be sent to the forwarded to the Core Network. On the downlink the Cluster Head multicasts received packets to the BSs in the Cluster. Each BS monitors the required transmitting power and the Downlink quality for the MT connected to it in order to decide autonomously whether or not to transmit to the MT. In this way unnecessary or high-power transmissions are avoided in this way.

    To the Core Network a Cluster appears as one 'virtual BS'. The Core Network only has to deal with the hand-over details when a MT moves from one Cluster to another. In this situation the hand-over destination cluster is decided upon co-operatively by the MT and the RRM unit in the Service Middleware layer. Re-routing to the hand-over destination is conducted by the MM unit in the Service Middleware layer.


        Clustered Diversity hand-over scheme in 4G (Source: 3)

     

    Movable Networks

    Among the diverse range of wireless devices that 4G will support there will be many that are not capable of cellular access because of impracticality due to antenna size, power consumption, etc. Instead these devices will have short-range communications capabilities allowing Ad Hoc networking with other devices. Thus, they can access the 4G backbone through other cellular capable devices. When any device connects to the backbone it is assigned an IP address and the device effectively becomes a MH (Mobile Host) that is part of a MN (Movable Network). If the MH and the gateway MT move away from each other there must be support services to allow the MH to be disconnected from the MN while staying connected to the backbone by being handed over to another access point or MT.

     

    Mobility Control

    Mobile devices based on IP need some form of mobility control so that data can continue to be routed to them correctly. However, the IP address is based on the Network ID and this may change as the user roams.

    Mobile IP is the mechanism that provides mobility control. It works on the principle of discovering, registering and tunneling to a temporary 'Care-of Address' (CoA) while the devices is on the move, away from where it first connected to the IP backbone. A MT on the move arranges for nodes within the Core Network known as Mobile Agents (MAs) and Home Agents (HAs) to redirect packets addressed to its original address, to its CoA. While the first packet has been redirected from the HA to the MA to the MT, the source is notified of the MA's address, and subsequent packets are sent straight to the MA bypassing the HA, thereby creating a 'tunnel'.

    Tunneling reduces the number of hops that data must undergo and also reduces the amount of control signaling required for mobility control. The value of this is especially appreciable when tunneling is applied to Ad Hoc networks.

    A device (lets call it Device A) joining a MN would use the MN's gateway to the backbone (eg. a MT with cellular access - lets call it B) as its MA. However, B, along with its MN, is itself moving, has an original HA and traversing MAs within the Core Network. Only the very first packet must endure a number of hops - from the HA of A to the HA of B to the MA of B to B to A. Subsequent packets however, are routed straight to the MA of B, then to B (as with any traffic to B) and finally on to A. As long as A stays part of the MN the HAs can be completely bypassed even though it is moving along with the MN.

     

    Wireless LAN Integration

    One of the major evolutionary steps on the path to 4G is the integration of Wireless LANs so that they can access the IP backbone of a 4G network.

    A Wireless LAN is an extension to wired LAN where it uses electromagnetic airwaves for communication whereas wired LAN does uses cables. Wireless LAN types include Infrared (IR) Technology, Spread Spectrum Technology, Frequency hopping, Direct sequence and Narrowband Technology.

    There are several advantages of using WLANs. They enable data to be transmitted over air, thus reducing cabling. WLANs offer productivity, convenience, and cost advantages over traditional wired networks such as increased installation speed, increased simplicity and flexibility, reduced cost-of-ownership and scalability. Also they combine data connectivity with user mobility, increasing flexibility as well as allowing ad-hoc and roaming access within a limited range.

    Since the 4G core network is basically an IP-based network connecting a Wireless LAN to the 4G backbone is similar in principle to connecting wired LAN in a wired Internet. This is done through a router with a radio transmitter capable of cellular access.

     

    HIPER LAN 2

    Wireless LAN data rates are presently far lower than the expected data rates for 4G. Thus, Wireless LAN technology will also need research to handle increased data rates.

    HIPER LAN 2 is one such broadband wireless technology. It operates in the 5 GHz frequency band and is intended to provide untethered connectivity for mobile devices in corporate, public, and home environments. It uses a new type of radio technology called Orthogonal Frequency Division Multiplexing (OFDM).

    HyperLAN will provide mobility and high-speed transmission with a raw over-the-air data rate of 54 Mbps at the physical layer as well as sustained throughput. For applications such as voice and video, the transmission speeds are somewhat lower at 20 Mbps.

     

    BlueTooth

    The fact that 4G networks will support Ad Hoc Networking has been made quite clear but how it will do this has not yet been elaborated upon. BlueTooth is most likely to be the standard that will be a part of the 4G standards allowing for this functionality.

    BlueTooth is a Radio Frequency standard that provides a low-cost, low-power solution with industry-wide support. It provides agreement at the physical level with specifications at both link layer and application layer. It enables wireless links between mobile computers, mobile phones, portable handheld devices, and connectivity to the Internet. The developers of BlueTooth aim to bypass the problems that come with both infrared and cable synchronising systems.

    The main features of BlueTooth include the fact that it is wireless, its inexpensive, you don't have to think about it because it works behind the scenes, and it communicates in an unlicensed frequency of 2.45 GHz radio spectrum, which was set aside by international agreement for the use of Industrial, Scientific and Medical devices (ISM) ensuring communication compatibility worldwide.

    These characteristics of BlueTooth make it the ideal standard to use for the support Ad Hoc networking in 4G. Although present data rates for BlueTooth are not high enough to be 4G-capable, research into this technology is expected to improve on the present performance.

    BlueTooth Specicfications

    Devices in a piconet share a common communication data channel. It has a total capacity of 1 Mbps, with headers and handshaking data consuming 20% of this capacity. A piconet has a master and up to seven slaves. The master transmits in even time slots, slaves in odd time slots. A data channel hops randomly 1,600 times/sec between the 79 (or 23) RF channels. Each channel is divided into time slots 625Ás long. Packets can be up to five time slots wide. Data in a packet can be up to 2,745 bits in length.

    Five Layers Of Wireless Communications

    The five layers are Application Program Interface libraries, Logical Link Control & Data, Adaptation Protocol, Physical link control, Data processing & transmission management and Transmission/reception. These layers distribute functional responsibility, the bottom layers handle the lowest level details and progressively higher layers handle ever more general concerns.

     

    Non-technical Factors

    Social Implications

    In an increasingly mobile phone-dependent society, we need to carefully consider what sort of social implications there can be as a result of the availability of such high level services practically anywhere, anytime.

    It might be the case that many will become totally hooked to their personal mobile device and it may affect their social skills. The availability of on-demand entertainment services will play a major role in this regard.

    Also, with the level of intelligence and inter-connectivity that PDAs and other personal devices are likely possess, they may end up running our lives more or less. We may become overly dependent on them to take care of all the details in our lives (eg. control home appliances automatically, seek out location-dependent information and services, etc). Alternately, they may be viewed as helping hands that free up our time and resources. The line between the two interpretations however, is quite thin.

    The most important social issue that is likely to come up time and time again is that of privacy. What personal information will be required to be stored, what part of this can be divulged publicly, what level of authentication and encryption will be required to secure communications - these are all questions that have to be answered but there are no straightforward answers. Solutions will most probably be found in legislation and it is quite likely that not everyone will agree with these.

     

    Economic Implications

    Apart from the technological challenges there are a number of economic and political challenges that will also come into play. It is not just a case of ‘best technology prevails’.

    The situation in a decade’s time could be such that strict adherence to standards is not practiced despite years of effort for a stramlined unified standard. In fact, it may not be practical for a single unified standard to operate. Instead, quick and easy software solutions are found for continued interoperability. This is a very open situation where developments occur freely and uncontrolled. This can only be fuelled by the availability of software solutions and high user demand and support in all sectors.

    Alternately, it could be the case that tight regulation is needed in light of personal integrity and security issues. Central bodies may have to place the technology developers and distributors under tight scrutiny to make sure they conform to the rules. This, and higher complexity of systems resulting from the lack of an open environment, may push prices up too.

    A third scenario may also come to exist where service providers may be able to provide a high level of service but the technology is so expensive that it can only be afforded by a relatively small proportion.

    Assuming that widely accessible and affordable systems are in place within the next decade 4G systems will have a major effect on the economy and the way business is carried out. Higher levels of efficiency will be facilitated by the superior communications systems. For example, video Telephony will eliminate or reduce the need for 'face-to-face' meetings and the information and transaction services will be avaiabilityon the move.

     

    Health Issues

    The main concern, apart from mental health issues relating to social implecations, is that of radiation levels. The effects of exposure to radio transmissions are still being researched. Although there is no unanimous, concrete connection between mobile devices and deterioration of health, the heavier, more condensed traffic characteristics of future generation mobile networks do pose a risk that must be studied in more detail.

     

    Conclusion

    Within a matter of years the demand for mobile data services will outgrow the advancements of 3G. 4G will feature very high data rates and primarily multimedia services facilitated by various architectural and operational improvements. It completes the transition from circuit switching to packet switching, a much more efficient approach.

    This does however need a lot of research to address issues and challenges that stand in the way. As problems are solved and practical solutions are found it will become possible for concrete standards to be developed. Many existing standards also need to be revised so that they can be better suited for 4G. There are already a number of telcos such as NTT DoCoMo of Japan that have begun active experimentation and testing of key technologies that will be part of 4G. However, it is extremely important not to be carried away with technological development alone. In this process we do need to consider social, economic, ethical and health-related issues.

     

    Glossary

    Ad Hoc Networking: Networks formed without any central administration or infrastructure.

    Backbone: Foundation of 4G network. The packet-switching heart, also known as the IP Backbone Network

    Cellular: Form of communication where the signal is derived from land-based terrestrial stations. Each such station is located near the middle of its own cell. Thus moving from A to B a mobile user may be travelling across a number of cells dynamically changing base stations that are relaying the data.

    Mobile: Mobile is a description for devices that can be used anytime, anywhere. Sometimes used synonymously with 'wireless' but the subtle difference is important.

    Wireless: Communication through electro-magnetic waves, i.e via the air interface as opposed to wires.

     

    Multiple Choice Review Questions

    (1) Which of these are not part of the characteristics of 4G?

      (a) Software Dependency
      (b) Fully Converged Services
      (c) Diverse User Devices
      (d) Ubiquitous Mobile Access
      (e) Multirate management

    (2) What does SGSN stand for?

      (a) Serial Gateway Supporting Node
      (b) Supporting GPRS Support Node
      (c) Supporting GGSN Support Node
      (d) Supporting Gateway Supporting Node

    (3) What does MSC stand for?

      (a) Master Sequence Controller
      (b) Master Switching Controller
      (c) Master Switch Controller
      (d) Master Switching Control

    (4) What is the expected maximum data rate for 4G?

      (a) 100Mbps
      (b) 100Kbps
      (c) 10Mbps
      (d) 200Kbps

    (5) What application will require BlueTooth?

      (a) Ad-Hoc Networking
      (b) Desktop Publishing
      (c) Circuit Switching
      (e) Packet Networking

    (6) What are some of the major architectural differences exist between 3G and 4G?

      (a) The RNC acts as a BS in a cluster-type RAN configuration.
      (b) The circuit-switching elements are removed in 4G.
      (c) A VOIP Gateway is used to connect to the PSTN and ISDN networks
      (f) All of the Above

    (7) Which of these is not a function of the Service Middleware in the IP Core Network?

      (a) Media Conversion
      (b) Radio Resource Managment
      (c) Wireless Data transmission
      (d) Mobility Management

    (8) Why are cell sizes likely to be smaller in 4G?

      (a) Higher frequency bands are utilised for data transmission
      (b) At higher data rates the signal must be received at a higher SNR threshold.
      (c) A and B
      (d) Data is transmitted at lower power
      (e) A and D

    (9) What Location Management feature does 4G support?

      (a) Concurrent Location Registration
      (b) Concatenated Management
      (c) Collated Location Registration
      (d) Concatenated Location Registration

    (10) In the clustered diversity hand-over scheme that is used in 4G, the __________ is dynamically assigned to perform signal-processing combine the multiple signals into one:

      (a) Temporal Agent
      (b) Cluster Head
      (c) Cluster Agent
      (d) Temporary Cluster Head

     

    Answers:

    1)  e
    2)  b
    3)  b
    4)  a
    5)  a
    6)  d
    7)  c
    8)  c
    9)  d
    10) a

     

    References

    1. Arango, M.; 2001; “Architecture Issues in 4G Networks”; March 2001; Sun Microsystems Laboratories
      Kanter, T.; 2001; “An Open Service Architecture for Adaptive Personal Mobile Communications”; December 2001; IEEE Personal Communication
    2. Yumida, H., Imai, K., Yabusaki, M.; 2001; “IP-Based IMT Network Platform”; October 2001; IEEE Personal Communications
    3. Otsu, T., Okajima, I., Umeda, N., Yamao, Y.; 2001; “Network Architecture for Mobile Communications Systems Beyond IMT-2000”; October 2001; IEEE Personal Communications
    4. Stallings, W.; 2000; “Data & Computer Communications”; Sixth Edition; Prentice Hall
      Perkins, C. R.; 1997; “Mobile Networking Through Mobile IP”;
    5. http://www.computer.org/internet/v2n1/perkins.htm; Accessed on 25 May 2002
    6. Proxim White Paper; 2000“What is a Wireless LAN?”
    7. http://www.howstuffworks.com. Accessed on 25 May 2002
    8. http://www.xilinx.com/esp/bluetooth/tutorials/architecture.htm. Accessed on 24 May 2002
    9. Kazantzigis, M., kapoor, R., Gerla, M.; 2001; “Bluetooth: An Enabler for Personal Area Networking”; September/October 2001; IEEE Network
    10. Frodigh, M., Parkvall, S., Roobol, C., Johansson, P., Larsson, P.; 2001; “Future-Generation Wireless Networks”; October 2001; IEEE Personal Communications
    11. http://www.protocols.com/voip/protocol_stack.htm
    12. http://www.idg.net/crd_idgsearch_623132.html?sc=, accessed: 26/07/2002
    13. http://www.cio.com/archive/031501/invisible.html
    14. http://www.yellowfreightdrivers.com/Cell_Phone_Health_Issues.htm
    15. Priggouris, G., Hadjiefthymiades. S., Merakos., L.; 2000; “Supporting IP QoS in General Packet Radio Service”; September-October 2000; IEEE Network
    16. Evans, B. G., Baughan, K.; 2000; “Visions of 4G”; December 2000; Electronics and Communications Engineering Journal
    17. http://www.cellular.co.za/technologies/3g/3g.htm; Accessed 21 May 2002
    18. Webb, W.; 2001; “The Future of Wireless Communications”; Artech House Publishers
      http://www.nwfusion.com/research/2001/0702featside.html; accessed 21 May 2002


    Elias Abboud (00041172), Dinesh Gurram (00053746), James Pearce (00059345)