Wireless Future - Telenor

Figure 6 BRAIN QoS
architecture
62
App´s
QoS
IP
QoS
IP IP
Radio
QoS
H2 MAC H2 MAC
boundary ([15], [16]). This interface will attempt
to standardise the way layer 2 access technologies
interface to the IP layer – to support handover
and QoS at both layers in a generic way.
It is possible to perform all hand-over, QoS
and security at the IP layer but this is inefficient
when compared to a close co-operation between
layers 2 and 3. However, only by standardising
the IP2W (IP to Wireless) interface these efficiencies
can really be exploited for a range of
access technologies. In the case of HIPER-
LAN/2 a convergence layer will be written (see
below) to implement the interface but, equally,
Bluetooth or 802.11 link layers could be supported.
If the mobile host moves to another domain –
either supporting another access technology or
belonging to another authority – a macro-mobility
protocol, such as Mobile IP, could be used to
provide seamless handover. One of the research
areas of the BRAIN is to look at service adaptation
when, for example, a hand-over between
HIPERLAN/2 and UMMTS/GPRS takes place.
The adaptation will be achieved by co-operation
between the terminal software and elements in
the network.
In a similar way the BAN will support network
QoS. In the same way that the BRAIN has produced
an evaluation framework for mobility protocols
so it has for QoS protocols. Current QoS
schemes under evaluation include: IntServ,
IntServ within the BAN only, DiffServ with
bounded delay and IntServ over DiffServ.
IntServ is useful at the edge of the network where
the traffic becomes “lumpy” and a single large
multimedia stream can dominate the local flows.
Another area of research is how far the mobility
management and QoS protocols should be coupled.
Tightly coupled protocols tend to be inflexible,
uncoupled protocols inefficient, and so we
are looking at a loose coupling between the two.
The BAN is also responsible for the radio
resource management and admission control
parts of QoS.
end-to-end QoS
BRAIN
Access
Network
App´s
QoS
IP
QoS
IP IP
Radio
QoS
H2 MAC H2 MAC
The Air Interface
BRAIN has chosen a Wireless LAN standard –
HIPERLAN/2 – as the basis for its broadband
radio interface.
The BRAIN project will define enhancements to
the Physical and Data Link Control (DLC) layers
as well as define a BRAIN-specific convergence
layer in order to make HIPERLAN/2
suitable for IP transport in the usage scenarios
we have outlined and, thus, to implement the
BRAIN QoS architecture depicted in Figure 6.
Since HIPERLAN/2 will operate in unlicensed
spectrum and is intended to provide fixed network
QoS, there is a need to optimize the system
not only with respect to bandwidth efficiency –
as it is usually done for systems designed for
licensed deployment – but also with respect to
transmission robustness, aiming to maintain the
required QoS over the duration of an active link.
The combination and joint optimisation of layer
2 scheduling (on DLC level), link adaptation and
selected physical layer enhancements such as
multiple antenna concepts offer the possibility
to maintain the desired QoS for different classes
of traffic and, thus, protect especially real-time
applications from delays due to re-transmissions
and due to unpredictable errors on the wireless
link.
Specifically the BRAIN-enhanced HIPER-
LAN/2 system will support:
• Efficient transport of IP packets for all multimedia
applications;
• A QoS service to the IP network layer;
• Network layer mobility management protocols
– e.g. by providing paging;
• Hand-over of users to other BRAIN Wireless
routers (horizontal hand-over) as well as non-
BRAIN networks (vertical hand-over) – with
minimum delay/loss of packets;
• Unicast, Multicast and Broadcast services;
• A transparent service to the IP layer.
At the physical layer the BRAIN will look at
adaptive antennas, receiver diversity and smart
antenna techniques to improve system robustness.
In addition turbo codes and adaptive modulation
will be analysed as further optimisation
for HIPERLAN/2 aiming at an efficient use of
spectrum ([17]). Both an increase in system
robustness and spectrum efficiency will contribute
to improving QoS for IP traffic.
Telektronikk 1.2001