2. Advanced Mobile Phone System : It transmits speech signals
employing FM, and important control information is transmitted in
digital form using FSK. The idea of dividing the entire service area
into logical divisions called cells. Each cell is allocated one specific
band in the frequency spectrum.
AMPS uses a cell radius of 1 to 16 miles, depending on various
factors such as density of users and traffic intensity.
AMPS is that it allows both cell sectoring and splitting.
It is also sufficient to have a low-power MS (about 4 watts or less)
and a medium-power BS (about 100 watts).
AMPS is capable of supporting about 100,000 customers per city,
and the system is aimed to reduce blocking probability to about 2%
during busy hours.
AMPS
3. Frequency allocation in AMPS is done by dividing the entire
frequency spectrum into two bands—Band A and Band B.
Frequencies are allocated to these bands
Characteristics of AMPS
4. Three identification numbers are included in the AMPS system to
perform various functions:
1. Electronic serial number (ESN): A 32-bit binary number uniquely
identifies a cellular unit or a MS and is established by the
manufacturer at the factory.
2. System identification number (SID): A unique 15-bit binary
number assigned to a cellular system. A MS should first transmit
this number before any call can be handled. The SID serves as a
check and can be used in determining if a particular MS is
registered in the same system or if it is just roaming.
3. Mobile identification number (MIN): A digital representation of
the MS’s 10-digit directory telephone number.
Operation of AMPS
6. Operation of AMPS
There are two important control channels:
1. forward control channel (FOCC) from the BS to the MS.
2. reverse control channel (RECC) from MS to BS, both operating at
10 kbps.
And two Voice Channels :
Forward voice channel (FVC): FVC is used for one-to-one
communication from the BS to each individual MS.
Reverse voice channel (RVC): Reverse voice channel is used for
one-to-one communication from the MS to the BS during calls in
progress and is assigned by the BS to a MS for its exclusive use.
7.
8. When a BS powers up, it has to know its surroundings before providing
any service to the MSs.
It scans all the control channels and tunes itself to the strongest channel.
Then it sends its system parameters to all the MSs present in its service
area. Each MS updates its SID and establishes its paging channels only if
its SID matches the one transmitted by the BS. Then the MS goes into the
idle state, responding only to the beacon and page signals.
If a call is placed to a MS, the BS locates the MS through the IS-41
message exchanges. Then the BS pages the MS with an order.
If the MS is active, it responds to the page with its MIN, ESN, and so on.
The BS then sends the control information necessary for the call, for
which the MS has to confirm with a supervisory audio tone (SAT),
indicating completion of a call.
If a call is to be placed from a MS, the MS first sends the origination
message to the BS on the control channel. The BS passes this to the IS-41
and sends the necessary control signals and orders to the MS. Thereafter,
both MS and BS shift to the voice channels. A FVC and RVC control
message exchange follows to confirm the channel allocation. Then the
actual conversation starts.
General Working of AMPS Phone System
9. IS-41 is an interim standard that allows handoffs between BSs under
control of different MSCs and allows roaming of a MS outside its home
system. In order to facilitate this, the following services need to be
provided:
Registering of the MS with a visiting MSC.
Allowing for call origination in a foreign MSC.
Allowing the MS to roam from one foreign system to another.
In addition to the three identification numbers described for AMPS, a
switch number (SWNO) is used to identify a particular switch within a
group of switches with which it is associated. It is the parameter derived
from the concatenation of the SID and switch identification (SWID).
IS-41 functionality is in the application layer to support the mobile
application part, the application service element, and the transaction
capabilities application part. The association control service element
(ACSE) is used to correlate two applications (i.e., setting up an association
between the two entities A and B).
ROSE is invoked during the exchange of IS-41 messages using an
asymmetric client/server–based model in which a client requests a service
and the server responds with an appropriate reply.
IS-41
13. The various operations supported by IS-41 are as follows:
Registration in a new MSC: When a mobile terminal moves into a new area
(served by a different MSC), it has to register with the new serving MSC.
Calling an idle MS in a new system: When a call is to be routed to a MS in a new
system, the HLR of the home MSC contacts the VLR of the latest visiting system
and, after appropriate authentication and exchange of IS-41 messages, allows
the call to be routed to the MS in the visiting system.
Call with unconditional call forwarding: In case the visiting MS has
unconditional call forwarding in effect, the visiting MSC sends a location request
response to the home MSC, which contains the identifier of the telephone to
which this call is to be forwarded.
Call with no answer: In case the visiting MS does not answer the call, the calling
terminal is issued an appropriate response and the call is disconnected.
Calling a busy MS: This follows the same pattern as for call with no answer,
except that a busy tone is conveyed to the calling terminal in case the MS does
not have call waiting. If the MS has call waiting, the MS is informed of the second
incoming call.
Handoff measurement request: A serving MSC can sometimes request an
adjacent MSC for a handoff measurement.
Recovery from failure at the HLR: This IS-41 procedure is used in the event of an
HLR failure. In case of failure the HLR sends an UNRELDIR (Unreliable Roamer
Data Directive INVOKE) to all the VLRs in its database.
Support Operations
14. GSM (Global System for Mobile communications or Groupe Speciale Mobile). The
main objective of GSM is to remove any incompatibility among the systems by
allowing the roaming phenomenon for any cell phone.
Specific functions of different constituents are as follows:
Base station controller (BSC): The main function of the BSC is to look over a
certain number of BTSs to ensure proper operation. It takes care of handoff from
one BTS to the other, maintains appropriate power levels of the signal, and
administers frequency among BTSs.
Mobile switching center (MSC): The MSC basically performs the switching
functions of the system by controlling calls to and from other telephone and
data systems.
Authentication center (AUC): AUC unit provides authentication and encryption
parameters that verify the user’s identity and ensure the confidentiality of each
call.
Equipment identity register (EIR): EIR is a database that contains information
about the identity of mobile equipment that prevents calls from being stolen and
prevents unauthorized or defective MSs.
GSM
15. GSM has been allocated an operational frequency from 890MHz to 960 MHz to
reduce possible interference, the MS and the BS use different frequency ranges.
GSM follows FDMA and allows up to 124 MSs to be serviced at the same time.
The frequency band of 25MHz is divided into 124 frequency division multiplexing
(FDM) channels, each of 200 kHz, and a guard frame of 8.25 bits is used in
between any two frames transmitted either by the BS or the MS.
GSM uses a variety of multiplexing techniques to create a collection of logical
channels.
Frequency Bands and Channels
16. The GSM system uses a variety of control channels to ensure uninterrupted
communication between MSs and the BS. Three control channels are used for
broadcasting some information to all MSs:
1. Broadcast control channel (BCCH): Used for transmitting system parameters,
(e.g., the frequency of operation in the cell, operator identifiers) to all the MSs.
2. Frequency correction channel (FCCH): Used for transmission of frequency
references and frequency correction burst of 148 bits length.
3. Synchronization channel (SCH): Used to provide the synchronization training
sequences burst of 64 bits length to the MSs.
Three common control channels are used for establishing links between the MS
and the BS, as well as for any ongoing call management:
1. Random-access channel (RACH): Used by the MS to transmit information
regarding the requested dedicated channel from GSM.
2. Paging channel: Used by the BS to communicate with individual MS in the cell.
3. Access-grant channel: Used by the BS to send information about timing and
synchronization.
Channels in GSM
17. Channels in GSM
Two dedicated control channels are used along with traffic channels to serve for
any control information transmission during actual communication:
Slow associated control channel (SACCH): Allocated along with a user channel,
for transmission of control information during the actual transmission.
Stand-alone dedicated control channel (SDCCH): Allocated with SACCH; used for
transfer of signaling information between the BS and the MS.
Fast associated control channel (FACCH): FACCH is not a dedicated channel but
carries the same information as SDCCH.
19. Several identity numbers are associated with a GSM system, as follows:
International mobile subscriber identity (IMSI).
Subscriber identity module (SIM): Every time the MS has to communicate with a
BS, it must correctly identify itself. A MS does this by storing the phone number,
personal identification number for the station, authentication parameters, and
so on in the SIM card. Smart SIM cards also have a flash memory that can be
used to store small messages sent to the unit. The main advantage of SIM is that
it supports roaming with or without a cell phone, also called SIM roaming.
Mobile system ISDN (MSISDN).
Identity Numbers Used by a GSM System
20. Location area identity (LAI).
International MS equipment identity (IMSEI).
MS roaming number (MSRN).
Temporary mobile subscriber identity (TMSI): As all transmission is sent
through the air interface, there is a constant threat to the security of information
sent. A temporary identity is usually sent in place of IMSEI.
Identity Numbers Used by a GSM System
21. Interfaces, Planes, and Layers of GSM
Authentication process
in GSM
Functional planes in GSM.
22. Handoff in GSM is divided into four major categories:
Intracell/intra-BTS handoff: The channel for the connection is changed within
the cell (usually when higher interference occurs).
Intercell/intra-BSC handoff: In this case, the change is in the radio channel
between two cells that are served by the same BSC.
Inter-BSC/intra-MSC handoff: A connection is changed between two cells that
are served by different BSCs but operate in the same MSC.
Inter-MSC handoff: A connection is changed between two cells that are in
different MSCs.
Basic handoff: When the MS travels from its home MSC to a foreign MSC.
Subsequent handoff: When the MS travels from one foreign MSC to another
foreign MSC
Handoff
Inter-MSC handoff
23. The short message service (SMS) is the ability to send or receive a text
message to or from mobile phones.
The GSM system supports SMS messages using unused bandwidth and
has several unique features. SMS features confirmation of message
delivery.
SMS can be sent and received simultaneously with GSM voice, data, and
fax calls.
SMS text is not sent directly from a sender to the receiver but is always
processed via a SMS center instead.
A single SMS can be up to 160 characters of text in length, and these 160
characters comprise a combination of words, numbers, or alphanumeric
characters.
Non-text–based SMSs (for example, in binary format) are also supported.
There are ways of sending multiple SMS. For example, SMSs
concatenation (stringing several short messages together) and SMS
compression (getting more than 160 characters of information within a
single short message) have been defined and incorporated in the GSM
SMS standards
Short Message Service (SMS)
24. PCS (personal communications services) employs an inexpensive,
lightweight, and portable handset to communicate with a PCS BS.
PCS encompasses the whole spectrum of communication services
ranging from an ordinary cellular telephone to cable television.
The PCS can be classified into high-tier and low-tier standards. High-
tier systems include high-mobility units with large batteries, such as
a MS in a car.
Low-tier systems include systems with low mobility, capable of
providing high-quality portable communication service over a wide
area. The PCS low-tier standards based on personal access
communications systems (PACS) and digital European cordless
telecommunications (DECT) .
PCS
26. Chronology of PCS Development
CT2 (Cordless Telephone) operates using FDMA with a speech rate of 32
kbps using adaptive differential pulse code modulation (ADPCM). The
transmitter data rate is 72 kbps. CT2 uses TDD, which allows BS and MS to
share one channel.
DECT (Digital European Cordless Telecommunications) standard is a
second generation cordless telephone system. DECT operates on
frequencies ranging from 1880MHz to 1900MHz and uses ADPCM with 32
kbps speech rate.
CT2 TDD slot (first generation)
DECT TDD slot
(second-generation)
27. The Bellcore view of PCS is based on five different access services
provided between the Bellcore client company (BCC), the BCC network,
and the PCS wireless provider network as follows:
1. PCS access service for networks (PASN) is a connection service to and from
the PCS service provider (PSP).
2. PCS access service for controllers (PASC) is a service for use with PCS
wireless provider (PWP) across radio channels and some type of automatic
link transfer capability.
3. PCS access service for ports (PASP) is an interface into PWP.
4. PCS service for data (PASD) is a database information transport service.
5. PCS access service for external service providers (PASE) is used to support
specialized PCS services like voice mail, paging, and so on.
Bellcore PCS Reference Architecture: The air interface A connects the MS
with the radio port (RP) which is used among other things to convert the
air interface to or from a wire or fiber signal. The RPs are connected
through the port (P) interface to the radio port control unit (RPCU).
Bellcore View of PCS
28. Description of the PCS Air
Interface : PCS uses TDMA for
channel access. The reverse
frame format for PCS, with a
duration of 2.5 ms, Eight
frames are multiplexed
together to create a
superframe 20 ms in duration.
The downlink slot duration is
312.5 μs, and eight such slots
are present in a frame to give
a frame of 2.5 ms. The
superframe consists of eight
such frames for a total
duration of 20 ms, which is
similar to the uplink
superframe. 15 bits CRC (cycle
redundancy check) is
calculated from slow and fast
channels for each burst. Also,
a 1 bit PCC (power control
channel) is set according to
individual systems.
Bellcore PCS architecture
Forward TDMA frame for PCS
29. IS-95 uses the existing 12.5MHz cellular bands to derive 10 different CDMA bands
(1.25MHz per band). Because the same frequency can be used even in adjacent
cells, the frequency reuse factor is 1. The channel rate is 1.228 Mbps (in chips per
second).
RAKE receivers are used to combine the output of several received signals.
Sixty-four-bit orthogonal Walsh codes (W0 to W63) are used to provide 64
channels in each frequency band. In addition to Walsh codes, long pseudo noise
(PN) codes and short PN codes are also used.
The logical channels of CDMA are the control and traffic channels.
The control channels are the pilot channel (forward), the paging channels
(forward), the sync channels (forward), and the access channels (reverse).
The traffic channels are used to carry user information between the BS and the
MS, along with signaling traffic. Four different rates are used.
When the user speech is replaced by the associated signal, it is called blank and
burst. When part of the speech is replaced by signaling information, it is called
dim and burst. The downlink or forward link has a power control sub-channel
that allows the mobile to adjust its transmitted power by ±1 dB every 1.25 ms. The
pilot channelW0 is always required.
There can be one sync channel and seven paging channels; the remaining fifty-six
channels are called traffic channels.
IS-95
30. Pilot channel: The pilot channel is used by the base station as a reference
for all MSs. It does not carry any information and is used for strength
comparisons and to lock onto other channels on the same RF carrier. The
signals (pilot, sync, paging, and traffic) are spread using high frequency
spread signals I and Q using modulo 2 addition. This spread signal is then
modulated over a high frequency carrier and sent to the receiver, where
the entire process is inverted to get back the original signal.
Sync channel: The sync channel is an encoded, interleaved, and
modulated spread-spectrum signal that is used with the pilot channel to
acquire initial time synchronization. It is assigned the Walsh code W32.
Paging channel: As the name suggests, the paging channel is used to
transmit control information to the MS. When the MS is to receive a call, it
will receive a page from the BS on an assigned paging channel. There is no
power control for the paging channel on a per-frame basis. The paging
channel provides the MSs system information and instructions.
IS-95
32. Access channel: The access channel is used by the MS to transmit control
information to the BS. The access rate is fixed at 4800 bps. All MSs
accessing a system share the same frequency. When any MS places a call,
it uses the access channel to inform the BS. This channel is also used to
respond to a page.
Forward traffic channels: Forward traffic channels are grouped into rate
sets. Rate set 1 has four elements: 9600, 4800, 2400, and 1200 bps. Rate
set 2 has four elements: 14,400, 7200, 3600, and 1800 bps. Walsh codes
that can be assigned to forward traffic channels are available at a cell or
sector (W2 through W31, and W33 through W63). Only 55 Walsh codes are
available for forward traffic channels. The speech is encoded using a
variable-rate encoder to generate forward traffic data depending on
voice activity. The power control sub-channel is continuously transmitted
on the forward traffic channel.
Reverse traffic channels: For rate set 1, the reverse traffic channel uses
9600, 4800, 2400, or 1200 data rates for transmission. The duty cycle for
transmission varies proportionally with the data rate being 100% at 9600
bps to 12.5% at 1200 bps. The reverse traffic channel processing is similar
to the access channel except for the fact that the reverse channel uses a
data burst randomizer.
IS-95
36. Rate set 1 reverse
traffic generation
Rate set 2 reverse
traffic generation
37. Power Control
Power control plays an important role in view of the fact that every
receiver gets the signals transmitted by all the transmitters. To ensure
maximum efficiency, the power received at the BS from all the MSs must
be nearly equal.
If the received power is too low, there is a high probability of bit errors,
and if the received power is too high, interference increases. Power
control is applied at both the MSs as well as the BS.
There are several different mechanisms that are used for power control
initiated either by the MS or the BS, and the control can be based on the
signal strength perceived by the BS or can depend on other parameters.
In open-loop power control at the MS, the MS senses the strength of the
pilot signal and can adjust its power based on that. If the signal is very
strong, it can be assumed that the MS is too close to the BS and the
power level should be dropped.
In closed-loop power control at the MS, power control information is sent
to the MSs from the BS. This message indicates either a transition up or
transition down in power.
In open-loop power control at the BS, the BS decreases its power level
gradually and waits to hear the frame error rate (FER) from the MS. If the
FER is high, it increases its power level.
38. The International Telecommunications Union-Radio
communications (ITU-R) developed the 3G specifications to
facilitate a global wireless infrastructure, encompassing terrestrial
and satellite systems providing fixed and mobile access for public
and private networks.
The key features of the IMT-2000 system are as follows:
1. High degree of commonality of design worldwide.
2. Compatibility of services within IMT-2000 and with fixed networks.
3. High quality.
4. Small terminal for worldwide use, including pico, micro, macro, and
global satellite cells.
5. Worldwide roaming capability.
6. Capability for multimedia applications and a wide range of services
and terminals.
IMT-2000
39. In 1992 the World Administration Radio Conference (WARC) specified the spectrum
for the 3G mobile radio system.
Europe and Japan followed the FDD specification. The lower-band parts of the
spectrum are currently used for DECT and PHS (Personal Handyphone System),
respectively. The FCC in the United States has allocated a significant part of the
spectrum in the lower band to 2G PCS systems. Most of the North American
countries are following the FCC frequency allocation. Currently no common spectrum
is available for 3G systems worldwide.
International Spectrum Allocation
40. The following services are provided by third-generation cellular systems:
High bearer rate capabilities, including
– 2 Mbps for fixed environment
– 384 kbps for indoor/outdoor and pedestrian environment
– 144 kbps for vehicular environment
Standardization work
– Europe (ETSI: European Telecommunications Standardization Institute) ⇒UMTS
(W-CDMA)
– Japan (ARIB: Association of Radio Industries and Businesses) ⇒ W-CDMA
– USA (TIA: Telecommunications Industry Association) ⇒ cdma2000
Scheduled service – Service started in October 2001 (Japan’s W-CDMA)
Services Provided by Third-Generation Cellular Systems
41. A harmonized 3G system based on the Operators Harmonization Group (OHG)
recommendation is required to support the following:
High-speed data services, including Internet and intranet applications.
Voice and non-voice applications.
Global roaming.
Evolution from the embedded base of 2G systems.
ANSI-41 (American National Standards Institute-41) and GSM-MAP core networks.
Regional spectrum needs.
Minimization of mobile equipment and infrastructure cost.
Minimization of the
impact of intellectual
property rights (IPRs).
The free flow of IPRs.
Customer requirements
on time.
Harmonized 3G Systems
42. The multimedia messaging service (MMS) is an open industry
specification developed by the WAP forum for the 3rd Generation
Partnership Program (3GPP).
MMS has been designed to allow rich text, color, icons and logos, sound
clips, photographs, animated graphics, and video clips and works over the
broadband wireless channels in 2.5G and 3G networks. MMS and SMS are
similar in the sense that both are store-and-forward services where the
message is first sent to the network which then delivers it to the final
destination.
MMS service can be used to send messages to a phone or may be
delivered as an email.
The main components of MMS architecture are:
MMS Relay—Transcodes and delivers messages to mobile subscribers.
MMS Server—Provides the “store” in the store-and-forward MMS
architecture.
MMS User Agent—An application server gives users the ability to view,
create, send, edit, delete, and manage their multimedia messages.
MMS User Databases—Contain records of user profiles, subscription
data, etc.
Multimedia Messaging Service (MMS)
43. The content of MMS messages is defined by the MMS conformance
specification version 2.0.0, which specifies SMIL 2.0 (synchronization
multimedia integration language) basic profile for the format and the
layout of the presentation.
Although MMS is targeted toward 3G networks, carriers all over the world
have been deploying MMS on networks like 2.5G using WAP, and it helps
in generating revenue from existing older networks.
Some of the possible application scenarios are as follows:
Next-generation voicemail—Makes it possible to leave text, pictures, and
even video mail.
Immediate messaging—MMS features “push” capability that enables the
message to be delivered instantly if the receiving terminal is on and
avoids the need for “collection” from the server.
With MMS, users have an unprecedented range of choices about how
their mail is to be managed. They can predetermine what categories of
messages are to be delivered instantly, stored for later collection,
redirected to their PCs, or deleted.
Mobile fax—Using any fax machine to print out any MMS message.
Sending multimedia postcards.
(MMS)
44. Network Reference Architecture :
Universal Mobile Telecommunications System (UMTS)
45. UMTS Release’99 architecture inherits a lot from the global system for
mobile (GSM) model on the core network (CN) side. The MSC basically
has very similar functions both in GSM and UMTS. Instead of circuit-
switched services for packet data, a new packet node, packet data access
node (PDAN), or 3G serving general packet radio services (GPRS) support
node (SGSN) is introduced.
The major changes in the new architecture are in the radio access
network (RAN), which is also called UMTS terrestrial RAN(UTRAN).
There is a totally new interface called Iur, which connects two
neighboring radio network controllers (RNCs).
This interface is used for combining macro diversity, which is a new
WCDMA-based function implemented in the RNC.
In 2G, the RAN is separated from the CN by an open interface, called “A”
in circuit-switched (CS) and Gb in packet-switched (PS) networks.
In 3G, the corresponding interfaces are called Iu Cs and IuPs. The circuit-
switched interface will utilize ATM, while the packet-switched interface
will be based on IP.
Universal Mobile Telecommunications System (UMTS)
46. UTRAN Architecture : UTRAN consists of a set of radio network subsystems
(RNSs).
The RNS has two main elements: Node B and a RNC. The RNS is responsible for
the radio resources and transmission/reception in a set of cells. A RNC is
responsible for the use of and allocation of all radio resources of the RNS to
which it belongs. The responsibilities of the RNC include :
Intra-UTRAN handoff.
Macro diversity combining and splitting of the Iub DataStream's.
Frame synchronization.
Radio resource management.
Outer loop power control.
Serving RNS relocation.
UMTS radio link control (RLC)
sub-layers function execution.
Universal Mobile Telecommunications System (UMTS)
47. UTRAN Logical Interfaces: In UTRAN, the protocol structure is designed
so that the layers and planes are logically independent of each other and,
if required, parts of protocol structure can be changed in the future
without affecting other parts.
The protocol structure contains two layers: the radio network layer (RNL)
and the transport network layer (TNL).
A general protocol model for UTRAN interfaces is RANAP (radio access
network application protocol).
Channels : Three types of channels are defined in UMTS:
Transport channels are described by how the information is transmitted
on the radio interface. the services offered by the physical layer to the
higher layers. A general classification of transport channels is into two
groups:
1. Common transport channels (where there is a need for in-band
identification
of the UEs when particular UEs are addressed)
2. Dedicated transport channels (where the UEs are identified by the
physical channel, i.e., code, time slot, and frequency)
Universal Mobile Telecommunications System (UMTS)
48. Common transport channel types:
– Random access channel (RACH): A contention-based uplink channel used for
transmission of relatively small amounts of data (e.g., for initial access or non–
real-time dedicated control or traffic data).
– ODMA (Opportunity driven multiple access) random access channel (ORACH):
A contention-based channel used in relay link.
– Common packet channel (CPCH): A contention-based channel used for
transmission of bursty data traffic.
– Forward access channel (FACH): Common downlink channel without closed-
loop power control used for transmission of relatively small amount of data.
– Downlink shared channel (DSCH): A downlink channel shared by several
UEs carrying dedicated control or traffic data.
– Uplink shared channel (USCH): An uplink channel shared by several UEs
carrying dedicated control or traffic data, used in TDD mode only.
– Broadcast channel (BCH): A downlink channel used for broadcast of
system information into an entire cell.
– Paging channel (PCH): A downlink channel used for broadcast of control
information into an entire cell allowing efficient UE sleep mode
procedures.
Channels
49. Dedicated transport channel types:
– Dedicated channel (DCH): A channel dedicated to one UE used in uplink
or downlink.
– Fast uplink signaling channel (FAUSCH): An uplink channel used to
allocate dedicated channels in conjunction with FACH.
– ODMA dedicated channel (ODCH): A channel dedicated to one UE used
in relay link.
Logical channels are described by the type of information they
carry. Two types of logical channels are defined: traffic and control
channels. Traffic channels (TCH) are used to transfer user and/or
signaling data. Signaling data consists of control information
related to the process of a call. Control channels carry
synchronization and information related to the radio transmission.
Channels
50. Control channels:
– Broadcast control channel (BCCH): A downlink channel for broadcasting system
control information.
– Paging control channel (PCCH): A downlink channel that transfers paging
information. This channel is used when the network does not know the location cell
of the UE, or the UE is in the cell-connected state (utilizing UE sleep mode
procedures).
– Common control channel (CCCH): Bidirectional channel for transmitting control
information between network and UEs. This channel is common used by the UEs
having no RRC connection with the network and by the UEs using common transport
channels when accessing a new cell after cell reselection.
– Dedicated control channel (DCCH): A point-to-point bidirectional channel that
transmits dedicated control information between a UE and the network. This
channel is established through the RRC connection setup procedure.
– Shared channel control channel (SHCCH): Bidirectional channel that transmits
control information for uplink and downlink shared channels between the network
and UEs. This channel is for TDD only.
– ODMA common control channel (OCCCH): Bidirectional channel for transmitting
control information between UEs.
– ODMA dedicated control channel (ODCCH): A point-to-point bidirectional channel
that transmits dedicated control information between UEs. This channel is
established through the RRC connection setup procedure.
Channels
51. Traffic channels:
– Dedicated traffic channel (DTCH): A DTCH is a point-to-point channel,
dedicated to one UE, for the transfer of user information. A DTCH can
exist in both uplink and downlink.
– ODMA dedicated traffic channel (ODTCH): An ODTCH is a point-to point
channel, dedicated to one UE, for the transfer of user information
between UEs. An ODTCH exists in relay link.
– Common traffic channel (CTCH): A point-to-multipoint unidirectional
channel for transfer of dedicated user information for all or a group of
specified UEs.
Physical channels are defined differently for FDD and TDD.
All physical channels follow four-layer structure of superframe, radio
frames, sub frames, and time slots/codes. Depending on the resource
allocation scheme, the configurations of sub frames or time slots are
different. All physical channels need guard symbols in every time slot. The
time slots or codes are used as a TDMA component so as to separate
different user signals in the time and the code domain.
Channels
