Enhanced Radio Access Technologies for Next Generation Mobile Communication phần 7 doc

CDMA2000 1X & 1X EV-DO 173

3.2 1xEV-DO

• Coverage & LBA

The coverage of the 1xEV-DO network refers to a zone where the service is provided

at a certain throughput or higher throughput, or a zone with a certain C/I level or

higher level. C/I refers to the ratio between signal and interception. “C” indicates

the transmission power from the base station, and “I” indicates all interception

signal power except carrier power C among the received power example of forward

LBA could be found in Table 5.

C

I









DO

= PTXM · gM00d



36

i=1

2

j=0

PTXM · gMijd+ 2

j=1

PTXM · gM0jd+N0 · W

Parameters Descriptions

PT xM Transmission power of the cell

gN0d Transmission loss between the AT and the AP

gMyd Transmission loss between Ith AP and the AT in Jth sector

Now Thermal noise

• Do System Capacity

The forward link capacity of the 1xEV-DO network is determined by the MACIndex

count that physically identifies the users. Table 6 shows the MAC Channel and

preamble use versus MACIndex, and total 59 MACIndex values can be used as

traffic channels:

In the channel card of the 1xEV-DO, there are 96 reverse channels. Therefore,

when there are three sectors, each sector will have 32 channels.

Unlike the CDMA 2000 1x network, in the 1xEV-DO network, it is the sector

throughput, not the number of subscribers, which must be managed for the operation

of the system. Depending on the location of the user and the number of users, the

actual sector throughput may drop below 2.4 Mbps, which is the maximum physical

throughput. Major factors that affect the throughput include the early termination

and multi-user diversity gain.

Early termination occurs when the terminal requests a DRC that uses multi slots

with repeated symbols, see Table 7. The terminal responds by sending an ACK

through the ACK channel when correct demodulation is made before receiving

all slots that the base station sends. When the base station receives the ACK, it

will terminate the transmission without repetition. In short, transmission will be

completed within a shorter slot time and the throughput will increase.

Multi-user diversity gain refers to an increase in sector throughput caused by

characteristics of the proportional fair scheduler. The scheduler allocates the slots

to the user in a relative better condition. Therefore, when there are multiple users,

it is highly likely that uses in better conditions will be selected, hence increasing

174 CHAPTER 5

Table 5. Forward LBA

1x EV-DO Forward Link

Parameters Value Symbol Equation

Average Throughput [bps] 64300

Bandwidth [Hz] 1228800

Bandwith [dB-Hz] 60895 a

Tranmitter (Base station)

BTS Tx Power [Watts] 20

As above in dBm 4301 b

BTS Antenna Gain [dBI] 17 c

BTS Cable Loss [dB] 2 d

BTS EIRP [dBm] 5801 e b+c–d

Receiver (Mobile)

MS Rx Antenna Gain [dBi] 0 f

Body Loss [dB] 3 g

Noise Figure (dB) 8 h

Thermal Noise [dBm/Hz] −166 I (–174)+h

Target PER [%] 2

(lor/No)req per Antenna [dB] 4 j

Multi-user Diversity Gain [dB] 225

Rx Diversity Gain [dB] –

MS Receiver Sensitivity [dBm] −101105 k 1+j+a

Log-normal Std. Deviation [dB] 8

Log-normal Fade Margin [dB] 103 l

Handoff Gain [dB] 41 m

Building Penetration Loss [dB] 15 n

Maximum Pass Loss [dB] 13492 o e-k+f-g-l+m-n

Cell Range [km] 154

the sector throughput. However, in case of the multi-user diversity gain, the sector

throughput does not increase but is saturated when the number of subscribers

reaches a certain level as shown in Figure 20:

• Scheduler

The 1xEV-DO system uses a proportional fair scheduler. The scheduler allocates

the Nth slot to the user with the largest DRCi(N)/ Ri(N). DRCi(N)is the DRC that

Table 6. MAC Channel and preamble use Versus MACIndex

MACIndex Use

0 And 1 Not Used

2 76.8kbps Control Channel

3 38.4kbps Control Channel

4 RA Channel

5 ∼ 63 Forward Traffic Channel, RPC Channel

Table 7. Number of slots and symbol repetition count for each DRC

Values per Physical Layer Packet Approximate Coding

Data

Rate

(kbps)

Number

of Slots

Number

of Bits

Number of

Modulation

Symbols

Provided

Number of

Modulation

Symbols

Needed

Number of

Full Sequence

Transmissions

Number of

Modulation

Symbols in

Last Partial

Transmission

Code Rate Repetition

Factor

38.4 16 1,024 2.560 24,576 9 1,536 1/5 9.6

76.8 8 1,024 2,560 12,288 4 2,048 1/5 4.8

153.6 4 1,024 2,560 6,144 2 1,024 1/5 2.4

307.2 2 1,024 2,560 3,072 1 512 1/5 1.2

614.4 1 1,024 1,536 1,536 1 0 1/3 1

307.2 4 2,048 3,072 6,272 2 128 1/3 2.04

614.4 2 2,048 3,072 3,136 1 64 1/3 1.02

1,228.8 1 2,048 3,072 1,536 0 1,536 2/3 1

921.6 2 3,072 3,072 3,136 1 64 1/3 1.02

1,843.2 1 3,072 3,072 1,536 0 1,536 2/3 1

1,228.8 2 4,096 3,072 3,136 1 64 1/3 1.02

2,457.6 1 4,096 3,072 1,536 0 1,536 2/3 1