Remember that each slot has 2560 chips.

2560/256 = 10 symbol can be sent in each slot.

For uplink case, remember that DPDCH and DPCCH are code multiplexed. Here 1 symbol is divided into I and Q component. Thus, 1 symbol can convey 1 bit for uplink case (with QPSK).

Thus, uplink DPDCH has 10 bit data in a slot with 256 SF.

For downlink case, DPDCH and DPCCH are time multiplexed.

Thus, 1 symbol can still convey 2 bits.

Thus, downlink has 20 bit data in a slot with 256 SF. However, remember that some of bits are allocated to DPCCH control information.

uplink transmission is continuos and changes in bit rate can be achieved by modifying the spreading factor of the code sequence being used.

Downlink:

Spreading factor is chosen to support the highest bit rate of TFCS.

The variable bit rate is implemented with discontinuous transmission (DTX), swithcing off the transmission during the DPDCH fields in certain time slots.

Note that if code multiplexing was used, each DPCH (DPCCH and DPDCH) requires two channelization codes, and is less efficient.

Second, the control channel must always be present because of the power control mechanism. But, what if there is no user data?

This will result in a pulsed transmission, which is not a problem in the downlink, as common channels (CPICH etc) will be sent all the time.

In the uplink, however, the discontinous transmission with time multiplexing would cause severe electromagnetic problems.

However, there is a single DPCCH with a fixed spreading factor 256.

The below depicts channelization and scrambling for multiple uplink DPDCHs.

The below shows the transmission with multiple downlink DPDCHs

Note that DPCCH contains TFCI (transport format combination indicator).

This means that TFCI will apply to all DPDCHs at the same time.

Also, spreading facotrs for DPDCHs are the same.

Note that DPDCH data rate varies frame by frame.

Two main categories: (1) dedicated and (2) control

1. Dedicated physical channels

a. DPDCH (Dedicated Physical Data Channel):

carries DCH transport channel.

As with DCH, this exists both in the uplink and downlink.

closed loop power control (1500 Hz/sec)

b. DPCCH (Dedicated Physical Control Channel):

relates to DPDCH and transmits physical layer signal information (e.g., power control commands and synch. sequences)

In the uplink, it is code multiplexed with DPDCH.

In the downlink, it is time multiplexed with DPDCH.

Note that this has nothing with DCH or DCCH or DTCH!

2. Physical control channels

a. P-CCPCH (Primary Common Control Physical Channel):

only in the downlink.

fixed bit rate of 30kbps (spreading factor 256)

carry the BCH transport channel.

b. S-CCPCH (Secondary Common Control Physical Channel):

carry the PCH and FACH transport channels.

only in the downlink.

different bit rates.

c. SCH (Synchronization Channel):

used for cell search and the first channel that UE needs to know.

allow synchronization at frame and code sequence of P-CCPCH.

d. CPICH (Common Pilot Channel):

transmits pre-defined bit sequence in downlink with 30kbps

allows UEs to measure power of cells

e. PRACH (Physical Random Access Channel):

uplink direction; carries RACH transport channel

open loop power control

f. HS-PDSCH (High Speed Physical Downlink Shared Channel):

carries HS-DSCH transport channel; multicode transmission with spreading factor 16

2ms frame with 3 slots

QPSK or 16-QAM

HARQ

g. HS-SCCH (High Speed Shared Control Channel):

fixed bit rate of 60kbps carry downlink signal for HS-DSCH.

Data will come soon.. be ready.

——————–

No transport related but

a. AICH (Acquisition Indicator Channel):

used for PRACH response

b. PICH (Paging Indicator Channel):

this is associated with S-CCPCH to which a PCH channel is mapped.

carries paging indicator that inform UEs that they need to decode the information of the PCH channel.