26-05-2012, 12:03 PM
W-CDMA (Wideband Code Division Multiple Access)
[attachment=23123]
ABSTRACT
W-CDMA (Wideband Code Division Multiple Access), UMTS-FDD, UTRA-FDD, or IMT-2000 CDMA Direct Spread is an air interface standard found in 3G mobile telecommunications networks. It is the basis of Japan's NTT DoCoMo's FOMA service and the most-commonly used member of the UMTS family and sometimes used as a synonym for UMTS.It utilizes the DS-CDMA channel access method and the FDD duplexing method to achieve higher speeds and support more users compared to most time division multiple access (TDMA) schemes used today. While not an evolutionary upgrade on the airside, it uses the same core network as the 2G GSM networks deployed worldwide, allowing dual-mode operation along with GSM/EDGE; a feat it shares with other members of the UMTS family.
The WCDMA air interface, referred also as UMTS terrestrial radio
access (UTRA), developed by the third-generation partnership project (3GPP). 3GPP has the goal to harmonize and standardize in detail the similar roposals from ETSI, ARIB, TTC, TTA, and T1. The chip rate of the system is 3.84 Mcps. The frame length is 10 ms and each frame is divided into 15 slots (2560 chip/slot at the chip rate 3.84 Mcps). Spreading factors range from 256 to 4 in the uplink and from 512 to 4 in the downlink. Thus, the respective modulation symbol rates vary from 960 k symbols/s to 15 k symbols/s (7.5 ksymbols/s) for FDD uplink. For separating channels from the same source, orthogonal variable spreading factor (OVSF) channelization codes are used. In the downlink, Gold codes with a 10-ms period (38400 chips at 3.84 Mcps) are used to separate different cells, with the actual code itself length 2-1 chips. In the uplink, Gold codes with a 10- 18 ms period, or alternatively short codes with a 256-chip period, are used to separate the different users.
WCDMA SPECIFICATION
ThE air interface description in the following is based on the 3GPP wideband CDMA specifications as listed in Table 6.2. The physical layer is specified in TS25 series of 3GPP specifications.
BANDWIDTH 5,10,15 MHZ
Spreading width Orthogonal variable spreading codes (OVSF)
Data rates 144 Kbps – 3.84 Mbps
Duplex FDD
PROTOCOL ARCHITECTURE
The air interface protocol architecture. The protocol architecture is similar to the current ITU-R protocol architecture, ITU-R M.1035. The air interface is layered into three protocol layers:
• The physical layer (layer 1, L1);
• The data link layer (layer 2, L2);
• Network layer (layer 3, L3).
The physical layer interfaces the medium access control (MAC) sublayer of layer 2 and the radio resource control (RRC) layer of layer 3. The physical layer offers different transport channels to MAC. A transport channel is characterized by how the information is transferred over the radio interface. Transport channels are channel coded and then mapped to the physical channels specified in the physical layer. MAC offers different logical channels to the radio link control (RLC) sublayer of layer 2. A logical channel is characterized by the type of information transferred. Layer 2 is split into following sublayers: MAC, RLC, packet data convergence protocol (PDCP) and broadcast/multicast control (BMC). Layer 3 and RLC are divided into control and user planes. PDCP and BMC exist in the user plane only. In the control lane, layer 3 is partitioned into sublayers where the lowest sublayer, denoted as RRC, interfaces with layer 2. the RLC sublayer provides ARQ functionality closely coupled with the radio transmission technique used.
Logical Channels
The MAC layer provides data transfer services on logical channels. A set of logical channel types is defined for different kinds of data transfer services as offered by MAC. Each logical channel type is defined by the type of information that is transferred. Logical channel types are depicted in Figure 6.3. Logical channels are classified into
two groups:
• Control channels for the transfer of control plane information.
• Traffic channels for the transfer of user plane information .
Control channel (CCH):
• Broadcast control channel (BCCH)
• Paging control channel (PCCH)
• Dedicated control channel (DCCH)
• Common control channel (CCCH)
• Traffic channel (TCH) Dedicated traffic channel (DTCH)
• ODMA dedicated control channel (ODCCH)
• ODMA common control channel (OCCCH)
Traffic channel (TCH) :
• Dedicated traffic channel (DTCH)
• ODMA dedicated traffic channel (ODTCH)
• Common traffic channel (CTCH)
[attachment=23123]
ABSTRACT
W-CDMA (Wideband Code Division Multiple Access), UMTS-FDD, UTRA-FDD, or IMT-2000 CDMA Direct Spread is an air interface standard found in 3G mobile telecommunications networks. It is the basis of Japan's NTT DoCoMo's FOMA service and the most-commonly used member of the UMTS family and sometimes used as a synonym for UMTS.It utilizes the DS-CDMA channel access method and the FDD duplexing method to achieve higher speeds and support more users compared to most time division multiple access (TDMA) schemes used today. While not an evolutionary upgrade on the airside, it uses the same core network as the 2G GSM networks deployed worldwide, allowing dual-mode operation along with GSM/EDGE; a feat it shares with other members of the UMTS family.
The WCDMA air interface, referred also as UMTS terrestrial radio
access (UTRA), developed by the third-generation partnership project (3GPP). 3GPP has the goal to harmonize and standardize in detail the similar roposals from ETSI, ARIB, TTC, TTA, and T1. The chip rate of the system is 3.84 Mcps. The frame length is 10 ms and each frame is divided into 15 slots (2560 chip/slot at the chip rate 3.84 Mcps). Spreading factors range from 256 to 4 in the uplink and from 512 to 4 in the downlink. Thus, the respective modulation symbol rates vary from 960 k symbols/s to 15 k symbols/s (7.5 ksymbols/s) for FDD uplink. For separating channels from the same source, orthogonal variable spreading factor (OVSF) channelization codes are used. In the downlink, Gold codes with a 10-ms period (38400 chips at 3.84 Mcps) are used to separate different cells, with the actual code itself length 2-1 chips. In the uplink, Gold codes with a 10- 18 ms period, or alternatively short codes with a 256-chip period, are used to separate the different users.
WCDMA SPECIFICATION
ThE air interface description in the following is based on the 3GPP wideband CDMA specifications as listed in Table 6.2. The physical layer is specified in TS25 series of 3GPP specifications.
BANDWIDTH 5,10,15 MHZ
Spreading width Orthogonal variable spreading codes (OVSF)
Data rates 144 Kbps – 3.84 Mbps
Duplex FDD
PROTOCOL ARCHITECTURE
The air interface protocol architecture. The protocol architecture is similar to the current ITU-R protocol architecture, ITU-R M.1035. The air interface is layered into three protocol layers:
• The physical layer (layer 1, L1);
• The data link layer (layer 2, L2);
• Network layer (layer 3, L3).
The physical layer interfaces the medium access control (MAC) sublayer of layer 2 and the radio resource control (RRC) layer of layer 3. The physical layer offers different transport channels to MAC. A transport channel is characterized by how the information is transferred over the radio interface. Transport channels are channel coded and then mapped to the physical channels specified in the physical layer. MAC offers different logical channels to the radio link control (RLC) sublayer of layer 2. A logical channel is characterized by the type of information transferred. Layer 2 is split into following sublayers: MAC, RLC, packet data convergence protocol (PDCP) and broadcast/multicast control (BMC). Layer 3 and RLC are divided into control and user planes. PDCP and BMC exist in the user plane only. In the control lane, layer 3 is partitioned into sublayers where the lowest sublayer, denoted as RRC, interfaces with layer 2. the RLC sublayer provides ARQ functionality closely coupled with the radio transmission technique used.
Logical Channels
The MAC layer provides data transfer services on logical channels. A set of logical channel types is defined for different kinds of data transfer services as offered by MAC. Each logical channel type is defined by the type of information that is transferred. Logical channel types are depicted in Figure 6.3. Logical channels are classified into
two groups:
• Control channels for the transfer of control plane information.
• Traffic channels for the transfer of user plane information .
Control channel (CCH):
• Broadcast control channel (BCCH)
• Paging control channel (PCCH)
• Dedicated control channel (DCCH)
• Common control channel (CCCH)
• Traffic channel (TCH) Dedicated traffic channel (DTCH)
• ODMA dedicated control channel (ODCCH)
• ODMA common control channel (OCCCH)
Traffic channel (TCH) :
• Dedicated traffic channel (DTCH)
• ODMA dedicated traffic channel (ODTCH)
• Common traffic channel (CTCH)