26-06-2013, 03:14 PM
4G Wireless Technology
[attachment=56044]
4G Wireless: Definition
• 4G Wireless:
– Defined by the ITU (International
Telecommunication Union).
– A 4G system targets peak data rates of
approximately 100 Mbps for high mobility
service.
– A 4G system targets peak data rates of
approximately 1 Gbps for low mobility/
fixed service.
– Shall support required channel bandwidths
from 5 to 20 MHz with an optional 40 MHz
channel allowed.
4G Wireless: Technologies used in 4G
• MIMO - Minimum antenna configurations.
– For the BS - a minimum of 2 Tx and 2 Rcv antennas
– For the MS - a minimum of 1 Tx and 2 Rcv antennas
• MIMO Techniques -
– Beam forming – makes use of multiple antennas to
steer or focus signal in a particular direction. Can
reduce adjacent site self-interference & add reach.
– SU-MIMO (Single User MIMO)
• Transmitting parallel & unique data streams in
the same frequency-time resource to a single
user. (Spatial Multiplexing)
• Improves individual users throughput.
• MIMO Techniques - continued
– MU-MIMO (Multiple User MIMO)
• Transmitting parallel & unique data streams
in the same frequency-time to multiple
users. (Spatial multiplexing)
• Improves sector/site capacity throughput.
– STBC - Space Time Block Coding
• The
4 G Wireless: Pre 4G – LTE
• LTE capable of 100 Mbps in DL and
50 Mbps in UL.
– This would be for a single user, single
site/sector with 20 MHz bandwidth for both
uplink and downlink under extremely favorable
RF conditions with adequate backhaul
capacity.
• Key Features of LTE
– Multiple access scheme – DL is OFDMA, UL is
SC-FDMA.
– Adaptive modulation. coding, H-ARQ and error
correction.
– Advanced MIMO (2 X 2, 4 X 4) spatial, single or
multi-user multiplexing techniques
– Support for both FDD and TDD
• 802.16-2004 (d) is often called Fixed WiMAX
– Fixed WiMAX does not support Mobility.
– Does not support 1 cell frequency reuse.
– Utilizes OFDM-256 FFT (Orthogonal
Frequency-Division Multiple)
– Also supports OFDMA 2048, but only
OFDM 256 FFT is specified in WiMAX
802.16d profiles.
– Supports both TDD (Time Division
Duplexing) and FDD (Frequency Division
Duplexing) services
4G Wireless: Implications
• While 4G will undoubtedly be a future
force, be aware that -
– Real 4G does not exist today
– Real 4G will require access to huge amounts of
last-mile spectrum that is not available today.
– Equipment R&D still in progress.
– Backhaul networks already under stress from
“3G” networks will need continuing capacity
upgrades
• High capacity ethernet connections over
fiber optic networks will probably be the
needed at all sites in the near future.
[attachment=56044]
4G Wireless: Definition
• 4G Wireless:
– Defined by the ITU (International
Telecommunication Union).
– A 4G system targets peak data rates of
approximately 100 Mbps for high mobility
service.
– A 4G system targets peak data rates of
approximately 1 Gbps for low mobility/
fixed service.
– Shall support required channel bandwidths
from 5 to 20 MHz with an optional 40 MHz
channel allowed.
4G Wireless: Technologies used in 4G
• MIMO - Minimum antenna configurations.
– For the BS - a minimum of 2 Tx and 2 Rcv antennas
– For the MS - a minimum of 1 Tx and 2 Rcv antennas
• MIMO Techniques -
– Beam forming – makes use of multiple antennas to
steer or focus signal in a particular direction. Can
reduce adjacent site self-interference & add reach.
– SU-MIMO (Single User MIMO)
• Transmitting parallel & unique data streams in
the same frequency-time resource to a single
user. (Spatial Multiplexing)
• Improves individual users throughput.
• MIMO Techniques - continued
– MU-MIMO (Multiple User MIMO)
• Transmitting parallel & unique data streams
in the same frequency-time to multiple
users. (Spatial multiplexing)
• Improves sector/site capacity throughput.
– STBC - Space Time Block Coding
• The
4 G Wireless: Pre 4G – LTE
• LTE capable of 100 Mbps in DL and
50 Mbps in UL.
– This would be for a single user, single
site/sector with 20 MHz bandwidth for both
uplink and downlink under extremely favorable
RF conditions with adequate backhaul
capacity.
• Key Features of LTE
– Multiple access scheme – DL is OFDMA, UL is
SC-FDMA.
– Adaptive modulation. coding, H-ARQ and error
correction.
– Advanced MIMO (2 X 2, 4 X 4) spatial, single or
multi-user multiplexing techniques
– Support for both FDD and TDD
• 802.16-2004 (d) is often called Fixed WiMAX
– Fixed WiMAX does not support Mobility.
– Does not support 1 cell frequency reuse.
– Utilizes OFDM-256 FFT (Orthogonal
Frequency-Division Multiple)
– Also supports OFDMA 2048, but only
OFDM 256 FFT is specified in WiMAX
802.16d profiles.
– Supports both TDD (Time Division
Duplexing) and FDD (Frequency Division
Duplexing) services
4G Wireless: Implications
• While 4G will undoubtedly be a future
force, be aware that -
– Real 4G does not exist today
– Real 4G will require access to huge amounts of
last-mile spectrum that is not available today.
– Equipment R&D still in progress.
– Backhaul networks already under stress from
“3G” networks will need continuing capacity
upgrades
• High capacity ethernet connections over
fiber optic networks will probably be the
needed at all sites in the near future.