HSPA Throughput and Congestion Control

Objective

At the end of the module the participant will be able to:

• Describe HSPA throughput in any condition.

• Know how system does in congestion situation.

Content

• Input parameters affecting HSDPA maximum data rate

• HSDPA Throughput

• Input parameters affecting HSUPA maximum data rate

• HSUPA Throughput

• HSPA Congestion

Input parameters affecting HSDPA maximum data rate

• UE category– number of codes, transport block size, inter TTI interval, 16QAM

support

• Terminal performance– sensitivity, interference suppression

• Number of assigned codes– up to 15 codes of SF16. 240 ksymbols/s per code

• Modulation– 16QAM or QPSK

* UE Category 11 and 12 support QPSK only

HS-DSCH Category

Maximum number of HS-DSCH

multi-codes

Minimum inter-TTI interval

Maximum MAC-hs TB

size

Total number of

soft channel

bits

Theoretical maximum PHY data

rate (Mbps)

Category 1 5 3 7298 19200 1.2

Category 2 5 3 7298 28800 1.2

Category 3 5 2 7298 28800 1.8

Category 4 5 2 7298 38400 1.8

Category 5 5 1 7298 57600 3.6

Category 6 5 1 7298 67200 3.6

Category 7 10 1 14411 115200 7.2

Category 8 10 1 14411 134400 7.2

Category 9 15 1 20251 172800 10.1

Category 10 15 1 27952 172800 14.0

Category 11* 5 2 3630 14400 0.9

Category 12* 5 1 3630 28800 1.8

UE Categories

Input parameters affecting HSDPA maximum data rate (cont.)

• Coding rate– turbo code rate 1/3 and rate matching

• Channel conditions– CQI and transport format mapping

– HARQ method

• Scheduler algorithm– round robin, C/I, proportional fair

HSDPA Throughput

• Ior = own cell interference observed by UE

• Ioc = other cell interference observed by UE

• Throughput is related to– UE travel speed

– Ior / Ioc ratio, vary depending on UE location

• Summary:– macro cell 850 kbps → 1.3 – 2.2 Mbps

– micro cell 1.4 Mbps → 3.5 – 5 Mbps

Ior/Ioc

Ior/Ioc

Input parameters affecting HSUPA maximum data rate

• UE category– number of codes, mininum SF, 2ms TTI support, transport block size

• Receiver performance– detector in Node B

• Number of assigned codes and spreading factor– 1 – 4 codes, min SF4 or SF2

• Coding rate– ACK/NACK feedback and selection data amount

E-DCH category

Maximum number of

E-DCH codes transmitted

Min. SFSupport for 10 and 2 ms TTI

EDCH

Max. number of bits of E-DCH

transport block transmitted

within10 ms / 2 msE-DCH TTI

Max. Bit Ratein Mbps within a

10 ms / 2 msE-DCH TTI

Category 1 1 SF4 10 ms TTI only 7110 / - 0.73

Category 2 2 SF4 10 ms and2 ms TTI 14484 / 2798 1.46 / 1.46

Category 3 2 SF4 10 ms TTI only 14484 / - 1.46

Category 4 2 SF2 10 ms and2 ms TTI 20000 / 5772 2 / 2.92

Category 5 2 SF2 10 ms TTI only 20000 / - 2

Category 6 4 SF2 10 ms and2 ms TTI 20000 / 11484 2 / 5.76

NOTE: When 4 codes are transmitted in parallel, two codes shall be transmitted with SF2 and two with SF4.

Input parameters affecting HSUPA maximum data rate (cont.)

• Channel conditions– interference level

• UE transmitter power– UE power class

• Scheduler algorithm

HSUPA Throughput

• Summary:

– macro cell 800 kbps → 1.3 Mbps

– micro cell 1.1 Mbps → 2.2 Mbps

HSPA Congestion

• Rel 99 speech/video call usually higher priority than HSxPA.

• Rel 99 packet switched and/or HSxPA must be downgraded in case of congestion.

• Resource– Node B Transmit Power

– Channelization Code

– Radio Interference

– Channel Elements

Serving cell

Cell in active set

Cell in active set

DOWN HOLD

HO

LD

Congested

Signal congestion in the active set

Data

Dat

a

Data