Transmission - 3DTV: Processing and Transmission of 3D Video Signals - page 110

maintenance are key features that make WiMAX more attractive than cable
and xDSL, especially in those places where the latter two technologies can-
not be used or their costs are prohibitive [4]. For example, in countries with
a scarce wired infrastructure, WiMAX can become part of the broadband
backbone. The WiMAX standard covers a wide range of fixed and mobile
applications. The fixed version is termed IEEE 802.16d-2004, which is for
fixed or slow position changing devices (e.g. personal computers, laptops).
The mobile version is termed IEEE 802.16e-2005, which is an amendment to
IEEE 802.16d-2004 to support mobility, targeting mobile devices travelling
at speeds of up to 120 km/h (e.g. smart phones). Mobile WiMAX is based on
an OFDMA air interface and supports a scalable channel bandwidth of 1.25
to 20 MHz. WiMAX is capable of offering a peak downlink data rate of up to
63 Mbps and a peak uplink data rate of up to 28 Mbps in a 10 MHz channel
bandwidth with MIMO antenna techniques and flexible sub-channelization
schemes. WiMAX is also competing for a place in the IMT-Advanced stan-
dard via the IEEE 802.16m, which is an amendment to IEEE 802.16-2004 and
IEEE 802.16e-2005. A theoretical data rate requirement for IEEE 802.16m is a
target of 1 Gbps in stationary mode and 100 Mbps in mobile mode.
4.3.3.2 3D Video Multicast/Broadcast
Unicast, multicast, and broadcast are three transmission methods that can be
used for multimedia communication applications, such as 3D video commu-
nications over IP wireline and wireless networks. Unicast is a point-to-point
communication between a single sender and a single receiver over a network,
such as downloading, streaming media on demand, and point-to-point
telephony. Multicast is the communication between a single sender and a
group of receivers that are participating in a multicast session over a network,
such as internet television. Multicast is more efficient than multiple unicasts
in terms of network resource utilization and server complexity. Broadcast
transmission connects a sender to all receivers that it can reach through the
network, such as broadcasting over a wireless link or a shared Ethernet link.
The offering of 3D video services, such as mobile 3DTV to mobile sub-
scribers using the streaming option over unicast or point-to-point connections
allows an unlimited number of TV channels to be offered to a limited number
of subscribers. However, it is limited both from a cost and technical view-
point when delivering such services to many subscribers at the same time.
This is due to the fact that if numerous recipients try to access the service
at the same time (e.g. during a live sports event), the network is going to
saturate and the operator will not be able to offer the service adequately with
the inevitable decline in QoS. Hence, better to limit the audience and prevent
a mass-market deployment of 3D video services.
Using an overlay broadcast access network technology is an alternative
approach to offer mobile TV and mobile 3DTV services for the mass market.
Globally, the research and development of 3D content delivery in the form of