McWiLL Air Interface Overview

1. www.xinwei.com.cn
McWill Air Interface Overview
- Concepts and schemes
By Huang Qihua
Beijing Xinwei Telecom Technology Inc.

2. 2McWiLL
Agenda
2010-08-17 Morning
Physical layer
2010-08-17 Afternoon
Data link layer

3. 3McWiLL
Forewords
Physical layer is the first and lower layer in the air interface
protocol stack. It afford all kinds of functions for bit stream
transmission in the air.
Physical layer bears data and voice services for upper layers via
transport channels on MAC sub-layer.
Physical layer’s functionality: Channel coding, modulation,
spreading, mapping, multiplexing, synchronization, power
control etc.

4. 4McWiLL
Objective
After the course of this training, you will
• Understand the physical layer protocol of
Mc-Will air interface
• Master the basic but key knowledge of the physical
layer
• Understand some of the most important physical
layer processes

5. 5McWiLL
Contents
Xinwei communication
Chapter 1 Outline
Chapter 2 physical signal & physical channels
Chapter 3 physical layer methodology
Chapter 4 part of performance evaluation

6. 6McWiLL
McWill Radio Access Network
L2 Tunnel
BTS #1
BTS #2BTS #2
InternetIP 网
Core Network
Access Network

7. 7McWiLL
Air Interface Protocol model

8. 8McWiLL
Physical layer’s responsibility
Signal’s transmission and reception
Coding/decoding and Error Control
Synchronization in both DL and UL
Random access to the network
Channel quality evaluation
Multiple-antenna signal processing
Interface to upper layer(s)

9. 9McWiLL
Concepts
 Sub Carrier Group （ SCG ）
 The McWill wide band access system is divided into 5 groups of frequency
bands, each having 128 sub-carriers in one Mega Hz
 Sequence ID
 A BTS must be assigned one and only one sequence ID
 To indicate the difference of 2 cells
 It determines preamble, raging and pilot sequences for a BTS
 Totally there are 16 sequenceIDs in McWill
 Preamble
 At the beginning of down link interval
 For cell search and time and frequency synchronization
 CS-OFDMA
 Code-spread technique on basis of OFDMA
 Sub-channel
 The minimum unit for radio resource assignment and scheduling
 A 2-D structure with 8symbols in time domain and 8 sub-carriers in
frequency domain
 In super slot (the last slot in DL or UL), it has 10 symbols in time domain

10. 10McWiLL
TDD/CS-OFDMA Frame Structure

11. 11McWiLL
Summary of FDD Advantages
Guard time of TDD fundamentally limits the
communication distance while FDD does not have such a
restriction.
TDD may not be backward compatible to existing FDD
wireless communication systems such as cellular phones.
Summary of TDD Advantages:
Flexibility of selecting a carrier for providing services.
Flexibility of providing dynamic asymmetric services for
both uplink and downlink.
Exploitation of full benefits of smart antenna technologies
leading to high capacity, high performance, and low cost.
Frequency Division Duplex (FDD)
Vs. Time Division Duplex (TDD)

12. 12McWiLL
Code Spread OFDMA for spreading gain
There are 5 subcarrier groups in 5MHz and there are 128 tones in each sub-carrier
group.
Every symbol is spread on 8 tones which are uniformly distributed in the 1MHz.
Symbols s(1),…,s(N) are first spread and then the results are modulated to 8 tones.
Hence, the energy of each symbol is spread on 8 subtones.
f
1MHz 1MHz1MHz 1MHz 1MHz
5MHz
16 16 16 16 16 16 16 16
f
s(1)
s(2)
s(N)
Code 1
Code 2
Code N

13. 13McWiLL
Code-Spread OFDMA for spreading gain
Code-Spread OFDMA signaling transmits signal with BTS specific
spreading and pilot.
At the receiver side, detection process provide up to 9dB spreading gain
to combat most interference.

14. 14McWiLL
Code-Spread + distributed mapping
Multi-path propagation causing time dispersion and
radio-channel frequency selectivity.

15. 15McWiLL
Optimal Combination CS-OFDMA
ff
f
f
f f
WCDMA
Best on signal fading
Worst on multipath
interference
Good on intercell
interference
OFDM
Best on multipath
interference
Bad on intercell
interference
Worst on signal fading
CS-OFDMA
Optimal tradeoff among
multipath interference,
intercell interference, and
signal fading

16. 16McWiLL
Radio Resource
McWill radio spectrum is decomposed into time-frequency 2-D frame
structure, with set of sub-carriers and slot comprising basic assignment
block (sub-channel).
Each BTS is assigned a set of control channels for access operations.
BCH: broadcast channel
RACH: random access channel
RARCH: random access response channel
RRCH: ranging response channel
In deployment, each BTS is assigned a set of BCH, RACH, RARCH, RRCH
that receives minimum amount of interference from neighboring BTSs
by utilizing the 2-D frame structure as is shown in the next page.

17. 1/06/06
17McWiLL
Common Channels in McWill
Frequency
Each BTS has a total 16X5x8/2=320 sub-channels in 5MHz.
SCG means sub-carrier group.
Time
SCG0
SCG4
TS1
16 traffic
channels
／ timeslot
／ 1MHz
8 OFDMA symbols
137.5ms
SCG3
SCG2
SCG1
TS2 TS4TS3 TS5 TS6 TS8TS7
Time
SCG0
SCG4
TS1
16 traffic
channels
／ timeslot
／ 1MHz
8 OFDMA symbols
137.5ms
SCG3
SCG2
SCG1
TS2 TS4TS3 TS5 TS6 TS8TS7
Frequency
BCH/RARCH/RRCH BCH/RARCH/RRCH RACHRACH
BTS 1 BTS 2

18. 18McWiLL
Cell Identification
• Cellular network, high
spectrum utility
• Support indoor coverage
• Support high-speed
mobility
• Build-before-break HO
• Support data, video,
voice services
CS-OFDMA
Mobile
Cellular
Deployments
Each BTS is assigned a sequence ID different from
its neighboring BTSs.
For each BTS, preamble signal, ranging signal, PN
mask and pilot signal are generated based on the
assigned sequence ID.
Terminal searches the strongest preamble signal
for synchronization and accordingly uses
associated ranging signal, PN mask and pilot
signal for ensuing ranging, random access, signal
detection and handoff operations.

19. 19McWiLL
Multiplex scheme: CS-OFDMA
Modulation: QPSK, 8PSKm, 16QAM, and 64QAM adaptive
Base station bandwidth: 5MHz
Spectrum efficiency ： up to 4.8b/s/Hz raw and 3b/s/Hz net
Maximum BTS NET Throughput: 15Mbps/5MHz
Link budget > 163dB
Typical coverage radius: City 2 ～ 3Km, suburban: 8 ～ 13km,
rural: 5 ～ 30km
Output Power per Antenna: 2W
McWiLL System Specifications

20. 20McWiLL
Contents
Xinwei communication
Chapter 1 Outline
Chapter 2 physical signal & physical channels
Chapter 3 physical layer methodology
Chapter 4 part of performance evaluation

21. 21McWiLL
OFDMA Signal
Sub-carrier interval 7.8125 kHz
Useful symbol length 128
us
OFDMA symbol
length
137.5
Prefix length 6
Postfix length 3.5
1 timeslot = 8 OFDMA symbols in time domain

22. 22McWiLL
Basic principles of OFDM
OFDM subcarrier spacing.

23. 23McWiLL
Basic principles of OFDM
OFDM modulation.

24. 24McWiLL
OFDM modulation by means of IFFT
processing.

25. 25McWiLL
OFDM time–frequency grid.
a 2-D structure

26. 26McWiLL
Orthogonal attributes
The term Orthogonal Frequency Division Multiplex is
due to the fact that two modulated OFDM subcarriers
xk1 (t) and xk2 (t) are mutually orthogonal over the
time interval mTu ≤t <(m+1)Tu, i.e.

27. 27McWiLL
Basic principle of OFDM
demodulation.

28. 28McWiLL
Cyclic-prefix insertion
Method and purpose

29. 29McWiLL
OFDM => OFDMA
OFDM as a user-multiplexing/multiple-access scheme

30. 30McWiLL
Synchronization signals
preamble – to maintain down link sync before random access and rough
frequency offset correction.
ranging – to initialize UT’s timing of transmission in the uplink. Ranging
process is triggered before the first time of RA, or after several times of
RA failure.
pilot – to track and correct the timing and frequency offset caused by
circuits’ inconsistency and air link’s change during communication.

31. 31McWiLL
Preamble
16 PN sequences in frequency domain
Frequency domain mapping(64 tones)
Time domain waveform
20 40 60 80 100 120
0
2
4
6
8
10
12
Amp
subcarrier index

32. 32McWiLL
Preamble
UT stores all of the preamble sequences indexed from 0-15
all the preamble signals are transmitted synchronously
UT may scan all of the supported carrier frequencies in the
first time, to initialize its radio frame synchronization.
UT also maintains a history list to record the scanning
priority, in order to save the synchronization time.

33. 33McWiLL
Ranging- uplink time alignment
The transmissions from the different mobile terminals should
arrive at the base station with a timing misalignment less than
the length of the cyclic prefix to preserve orthogonality
between subcarriers received from different mobile terminals
and thus avoid inter-user interference.

34. 34McWiLL
Ranging
24 ranging sequences for a sequence ID
Frequency domain mapping(96 tones)

35. 35McWiLL
time slot structure (D/U=5:3)

36. 36McWiLL
time slot structure (D/U=1~7)
DL to UL timeslot ratio can be flexibly configured in
EMS->L2 configuration->Air link configuration:

37. 37McWiLL
Normal TS sch & Super TS sch

38. 38McWiLL
Physical Channels
Physical Dedicated Channels
PDTCH (Physical downlink traffic channel)
PUTCH (Physical uplink traffic channel)
Physical Common Channels
PRCH (Physical Ranging Channel)
PRRCH (Physical Ranging Response channel)
PRACH (Physical Random Access channel)
PRARCH (Physical Random Access Response channel)
Other channels for Trunked Radio
PDSCH (Physical downlink shared channel)
PUSCCH (Physical uplink shared control channel)

39. 39McWiLL
Physical Common Channels
PBCH
2 adjacent SCHs: QPSK/ LF=4/Mobile type
PRRCH
1 SCH: QPSK/LF=3/Mobile type
PRACH
2 adjacent SCHs: QPSK/LF=4/Mobile type
PRARCH
2 adjacent SCHs: QPSK/LF=4/Mobile type

40. 40McWiLL
Contents
Xinwei communication
Chapter 1 Outline
Chapter 2 physical signal & physical channels
Chapter 3 McWill physical layer methodology
Chapter 4 part of performance evaluation

41. 41McWiLL
Signal processing in DL
Downlink: one antenna rx, multiple antennas tx

42. 42McWiLL
Signal processing in UL
Uplink: one antenna tx, multiple antennas rx

43. 43McWiLL
Scrambling
B=XOR(Stream A,Stream SC)
A- payload bit stream
SC- scrambling sequence, valued 0,1, with the length of 1536 bits
B-output bit stream after scrambling
Scrambling operation is to randomize the payload bits’ value
before they are transferred to channel coding module
Scrambling process doesn’t change payload’s size

44. 44McWiLL
Modulation Schemes
Four kinds of modulation is used in McWill

45. 45McWiLL
Modulation Schemes
Distribution of instantaneous power for different
modulation schemes. Same average power in all
cases.

46. 46McWiLL
Demodulated SNR evaluation
-2 -1 0 1 2
-2
-1
0
1
2
snr= 5
-2 -1 0 1 2
-2
-1
0
1
2
snr= 10
-2 -1 0 1 2
-2
-1
0
1
2
snr= 15
-2 -1 0 1 2
-2
-1
0
1
2
snr= 20

47. 47McWiLL
Channel Coding
RS(106,96): Shortened RS(31,29)
System bits: 96 bits = 6 words
Parity bits: 10 bits
96 bits = 1 Voice packet(G.729a) + 1 Mac PDU header
106 bits = 53 QPSK symbols = 1 SCH (QPSK,
LF=8,Stationary mode)
Can correct one code symbol error

48. 48McWiLL
Code Spread
Each sub-channel has 8 tones & 8or10 OFDMA symbols
The optimal Loading factor (code spread factor) is
determined via evaluating wireless channel’s frequency
selective character caused by multi-path during the radio
propagation.
In single path propagating scenario, different loading factor
results in different spreading gain:
)/8(10log*10LF LFG =

49. 49McWiLL
Code Spread
LF(4,6,7 or 8) symbols are always mapped to 8 sub-carriers
Assuming LF=6 in the example below

50. 50McWiLL
Mobility Detection
10 20 30 40 50 60 70 80 90 100
0
1
2
3
4
5
6
7
1
2
3
4
30
210
60
240
90
270
120
300
150
330
180 0
2
4
6
30
210
60
240
90
270
120
300
150
330
180 0
Fast fading
Spatial signature’s inconsistency in one sub-channel

51. 51McWiLL
Mobility Detection
Use the 2 pairs of pilots in the
monitored PBCHs when UT is in
IDLE state
Use all of the OFDMA symbols
except SOWs in the PTCH when
UT is in COMMUNICATING state

52. 52McWiLL
Mobility detection (stationary mode SCH)
A sub channel in a normal time slot
A sub channel in a super time slot
f
t
SOW
pilot
子
信
道
0 1 2 3 4 5 6 7 OFDMA符号8 9

53. 53McWiLL
Mobility detection (mobile mode SCH)
A sub channel in a normal time slot
A sub channel in a super time slot

54. 54McWiLL
Multiple antenna methods
Three fundamental benefits of multiple antennas:
Diversity gain. Use of the space-diversity provided by the multiple
antennas to improve the robustness of the transmission against
multipath fading.
Array gain. Concentration of energy in one or more given
directions via precoding or beamforming. This also allows multiple
users located in different directions to be served simultaneously
(so-called multi-user MIMO).
Spatial multiplexing gain. Transmission of multiple signal streams
to a single user on multiple spatial layers created by combinations
of the available antennas.

55. 55McWiLL
Beam-forming in McWill
BTS estimates the spatial signature for all of its communicating
terminals with the pilot symbols in their allocated UL sub-
channels.

56. 56McWiLL
Beam-forming- Necessity for RF Calibration
The 8 T/R boards have
naturally inconsistent
frequency response
In each T/R board, the
transmitter and receiver
circuits possibly have
different frequency
response, e.g. Gtx1 is not
equal to Grx1
The 8 T/R boars might
also have group delay
problem due to SAW
filters and other circuits

57. 57McWiLL
Coverage Enhancement
Smart Antenna
2 Watts + 18 dB Gain
Conventional
2 Watts + 0 dB Gain
Same scale, same terrain, same clutter, same location

58. 58McWiLL
Nulling Principle
Obtain preferred signal’s normalized spatial signature
Wu
Estimate interference’s normalized spatial signature
Wi
Find out an optimal weight Wopt(| Wopt|=1), such that
Wopt
H
* Wu=1, and
to minimize {| Wopt
H
* Wi |}

59. 59McWiLL
Signal Co-Channel
Interference
Signal Co-channel
Interference
BTS 1 BTS 2
Signal Co-Channel
Interference
Signal Co-Channel
Interference
Uplink Downlink
BTS 1 Receive BTS 2 Receive
BTS 1 BTS 2
Terminal 1 Receive Terminal 2 Receive
Signal
Co-channel
Interference
Co-channel
Interference
Signal
Signal
Co-channel
Interference
Co-Channel
Interference
Signal
Spatial nulling of Smart Antenna can drastically reduce
the co-channel interference.
Spatial Nulling

60. 60McWiLL
Contents
Xinwei communication
Chapter 1 Outline
Chapter 2 physical signal & physical channels
Chapter 3 physical layer methodology
Chapter 4 part of performance evaluation

61. 61McWiLL
SCDMA broadband technology integrates multiple antennas
processing, code spreading, OFDMA signaling and high rate
channel coding to achieve high spectrum efficiency under
multi-path fading and interference channel conditions.
Link level: Fast fading performance for uplink and
downlink
System level performance with smart antenna techniques
System level performance with integrated smart antenna
and dynamic channel allocation
Field Trial Results
Outline

62. 62McWiLL
Link Level Performance:
simulation architecture
Generic CS-OFDMA TX/RX architecture for link level simulation
X Dimension-
Beam-Forming
Modulation/
Code Spreading
IFFT
IFFT
···
FEC Encoding
FFT
FFT
···
Multi-Antenna/
Multi-carrier
signal detection
FEC Decoding
Multi-Antenna
Channel
Vector channel
estimation
TX bit stream RX bit stream

63. 63McWiLL
Uplink Performance: fast fading
TX: 1 antenna with CS-OFDMA
RX: 8 antenna with MMSE detection
FEC: RS (106,96) or Convolutional code
8 10 12 14 16 18 20 22 24
10
-4
10
-3
10
-2
10
-1
PER
Eb/N0 (dB)
8 RX Antennas, ITU-3A, Doppler 100Hz
QAM4, Rate=0.45, RS(106,96)
QAM4, Rate=0.68, RS(106,96)
QAM16, Rate=0.45, RS(106,96)
QAM16, Rate=0.68, RS(106,96)
6 8 10 12 14 16 18 20 22
10
-4
10
-3
10
-2
10
-1
PER
Eb/N0 (dB)
8 RX Antennas, ITU-3A, Doppler 200Hz
QAM4, Rate=0.45, RS(106,96)
QAM4, Rate=0.68, RS(106,96)
QAM16, Rate=0.5, CC
QAM16, Rate=0.75, CC

64. 64McWiLL
Uplink Performance: fast fading
5 10 15 20
10
-4
10
-3
10
-2
10
-1
PER
Eb/N0 (dB)
8 RX Antennas, ITU-3A, Doppler 300Hz
QAM4, Rate=0.45, RS(106,96)
QAM4, Rate=0.68, RS(106,96)
QAM4, Rate=0.5, CC
TX: 1 antenna with CS-
OFDMA
RX: 8 antennas with
MMSE detection
FEC: RS (106,96) or
Convolutional code

65. 65McWiLL
Downlink Performance: fast fading
TX: 8 antenna with CS-OFDMA and 2-Dimension Beam-Forming
RX: 1 antenna with MMSE detection
FEC: RS (106,96)
5 10 15 20
10
-3
10
-2
10
-1
E
b
/N
0
(dB)
PER
ITU3A, fd=300Hz, LF=6
Downlink, 1-D BF
Downlink, 2-D BF
6 8 10 12 14 16
10
-4
10
-3
10
-2
10
-1
E
b
/N
0
(dB)
PER
ITU3A,fd=200Hz, LF=6
Downlink, 1-D BF
Downlink, 2-D BF

66. 66McWiLL
System level performance:
configurations
Parameters value
Carrier frequency 2.3GHz
Maximum power per BTS
antenna
33dBm
Effective BTS Antenna
gain
15 dBi
Noise figure 5dB
Thermal Noise Power
density
-174dBm/Hz
Maximum TX power per
terminal antenna
25dBm
Terminal antenna gain 5 dBi/-15dBi
Terminal noise figure 5dB
Parameters Value
Cell number (1,3
sectors)
19
Frequency reuse 1
Cell radius 1.5KM/Macro-Cell
BTS antenna array
toplogy
Linear uniform array for
3 sectors
circular array for 1
sector,
antenna spacing 0.5 λ
Propagation
model
(BTS Ht=32m,
MS=1.5m,
d≥35m)
Lognormal fading
variance
8dB
( )( )
( )
10 10
10 10
[ ] 44.9 6.55log log ( ) 45.5
1000
35.46 1.1 log ( ) 13.82log ( ) 0.7
bs
ms c bs ms
d
PL dB h
h f h h C
= − + +
− − + +
Propagation model BTS and terminal configuration

67. 67McWiLL
System level performance: frequency reuse = 1
Spectrum efficiency under frequency reuse factor = 1
1. Single sector with circular antenna array
2. Single antenna selection at the terminal
3. Uplink slot : downlink slot = 5 : 3
4. Uplink nulling and downlink beam-forming
5. Adaptive modulation
System throughput (Mbps/ 5MHz)
PED A PED B
Downlink 7.08 5.15
Uplink 5.28 3.91
Total system throughput
(Mbps/5MHz)
12.36
9.06
Spectrum
efficiency （ bps/Hz/Cell ）
2.47 1.81

68. 68McWiLL
PART2:
L2 – Data link layer
Data link layer is between physical layer and
network layer
Data link layer is also called as L2
Data link layer has 3 sub layers
DAC - Data Access Control
VAC - Voice Access Control
MAC - Medium Access Control

69. 69McWiLL
Air Interface Protocol model

70. 70McWiLL
Content to be depicted
Data link layer process
Broadcast information
Ranging
Radom access
L1 report
Power control
handoff
Radio resource management
DCA
N equals 1
Load balance
MAC, VAC & DAC functionality will be explicated in another
L2 specific training project

71. 71McWiLL
Access to the Network

72. 72McWiLL
BCH information
PBCH sub channel structure
2 contiguous physical sub
channels
QPSK, loading factor 4
Mobile style pilot insertion
2 PBCHs Bear 96 bits
No RS coding
CRC padding
PBCH bound messages
BTS-BC-INFO-1/2/3/4
Paging
Paging-Sleep
Broadcast Data

73. 73McWiLL
BCH messages
BTS-BC-INFO-1
Airlink protocol version
System Frame Number
Current BCH’s SCG number
Antenna power
Network ID
BTS ID
Number of TSs
Rx Sensitivity
BTS-BC-INFO-2
BCH 、 RRCH 、 RARCH resource
information
BTS-BC-INFO-3
Max scale
Preamble scale
Tch_Scale
BTS-BC-INFO-4
BTS frequency
Scg mask
Year-Mon-Day-Hour-Min-Sec
Lower 16bit frame number

74. 74McWiLL
BCH-BC-Info-1/2/3/4 are sent repeatedly after 10 frames
In each group of 10 frames, the remaining frames are used to send Paging/Sleep
paging, OAM message and Broadcast Data
Sleep Paging has the highest priority
CPE will not boost ranging process when powered on, unless it has correctly received
all of the 4 BCH-BC-Info messages

75. 75McWiLL
Paging
Paging Priority
Paging Cycle
Active terminal
Sleeping terminal

76. 76McWiLL
Ranging- Uplink Timing Alignment
2 kinds of physical sub-channels is related
PRCH
PRCH – PRCH is actually a ranging signal with the duration of 128
us
There are 32 unique ranging sequences available for each
sequence ID
PRCH implies the sender’s temporary signature and its TDD timing
information
PRRCH
Sent by BTS to respond to a valid ranging attempt
PRRCH indicates the raging ID, with the timing offset and rough
out-loop power control information per UT
Fixed channel format: QPSK, loading factor 3, one mobile type SCH
A correct PRRCH may be followed by a RACH

77. 77McWiLL
Ranging process
Multiple terminals may send ranging signal in one
frame, thus result in collision
Back-off mechanism is adopted to avoid collision

78. 78McWiLL
PRACH Mapping
In one time slot of one SCG,
there can not be more than 1
pair of PRACHs to be configured.
The indices of the pair of SCHs
for the PRACHs and PRARCHs
are determined by BTS’s
sequence ID.
PRACH/PRARCH should not be
located in the last timeslot

79. 79McWiLL
RA - random access
Random access is implemented via PRACH with the
corresponding PRARCH
Contending resolution mechanism is also adopted in RA
process

80. 80McWiLL
RARCH message
6 types of RA messages
Random Access
Paging Normal Response
Paging Only Response
Handover Probe
Handover RA
RA_SLEEP
3 types of RAR messages
BW-Configuration
HO-Probe-RSP
RA_Sleep_RSP

81. 81McWiLL
Handoff
A terminal obtains its currently connected cell’s neighbour list on
registration, thus to determine the carrier frequencies on which the
preamble strength will be measured.
When a terminal is moving out from its currently connected cell and
approaching to a neighboring cell, It measures the signal quality and
compares it. The UT may establish a new connection with the neighbouring
cell to replace its current connection with the ‘old’ cell.
Handoff is a major feature in McWill system. A kind of Build-before-break
hand over method is adopted to keep the QoS of voice and data services.
Handoff process is largely related to mobility management, which has been
already in the Layer 3 training project.

82. 82McWiLL
Handoff - active set
Active set
A set of links that might become the serving link
Active_Set(:,1)=Preamble_ID
Active_Set(:,2)=Carrier_ID
Active_Set(:,3)=Antenna_ID
Active_Set(:,4)=Power //filtered preamble Power (dBm)
Active_Set(:,5)=TimeOffset
Active_Set(:,6)= TimeOffsetFilteringCount //The counter of time
offset filtering
Active_Set(:,7)= ExceedHandoffThCount // The counter of exceed
the Handoff Threshold
Active_Set(:,8)= Ppre_delta //fading up/down range of preamble
power
The maximum size of Active Set is MaxNumActiveSet.
The active set is sorted by descend order of Power.

83. 83McWiLL
Handoff - active set
Active set operation
AddToActiveSet()
If the being measured link is in the active set, the power
and time offset is filtered after the relative measurement.
RemoveFromActiveSet()
The serving link cannot be kick out form active set
ResortActiveSet()
The power measured should be within valid range if it is
saved or filtered

84. 84McWiLL
Handoff - measurement
Monitoring_Set is all physical links of BTS Neighbor List.
Active_Set includes those current serving link and links that may became
future serving link. Active_Set is a subset of Monitoring_Set.
Ta is Active_set measurement time interval.
Tm is Monitoring_Set measurement time interval. Where
Tp is time period for finishing all physical link. Where
T a
T m
T p
M o n it o r in g _ S e t
A c t iv e _ S e t
L L
( ( ) 1)m a
k
T NumOfActiveAntennaOfActiveCarrier k T= +∑
p carrier antenna mT N N T= × ×

85. 85McWiLL
Handoff - measurement
For McWill, the following event-triggered criteria are specified
during the periodical measurement:
Event 1. Serving cell becomes better than inter-frequency
measurement threshold.[=> stop measuring other frequencies]
Event 2. Serving cell becomes worse than inter-frequency
measurement threshold. [=> start to measure other frequencies]
Event 3. Neighbour cell becomes better than an offset relative to the
serving cell. [=> ready to trigger the HO ]
Event 4. Neighbour cell becomes better than relative threshold. [=>
remove it from monitoring set, and add it into active set]
Event 5. Neighbour cell becomes worse than relative threshold. [=>
kick it out of active set]

86. 86McWiLL
Handoff- Measurement

87. 87McWiLL
Build-before-break Handoff within McWill

88. 88McWiLL
Load balance based Handoff
Normal HO criteria
Signal power offset
Hysteresis
Time to trigger
LDB HO criteria
Serving BTS load
UT specific load
LDB HO Complies with
Normal HO principles
ping-pong HO avoidance

89. 89McWiLL
Load evaluation
BTS load is subject to by several parameters
transmission power
radio resource utility
BTS HW capability
Weighted user number
Weighted user number
number of ul time slots
number of dl time slots
number of active users
number of reserved and active trunk groups
min{allocated bw, min_BW}, unit kbps 。
1
_ _ _ _
( ) 3
128 ( _ _ )
N
i i
i
bw d St d bw u St u
Load ceil Ng
St d St u=
× + ×
= + ×
× +
∑
_St u
_St d
N
Ng
_ ibw u _ ibw d

90. 90McWiLL
EMS Parameter Configuration
FilterCoef
Smoothing filter coefficient for layer3 sequence measurement
filtering
Value range: 0~20 (unit: 1/20)
Measure update formula ：
Fn = a*Fn-1 + (1-a)*Mn
Where
Fn ： filtered sequence power at time n.
Fn-1 ： filtered sequence power at time n-1.
Mn ： temporary power at time n.
a = (k/20), k is the configured Filter coefficient.

91. 91McWiLL
St: Serving BTS signal strength threshold for inter-frequency measurement
10
A value relative to -100(dBm)
If the serving BTS preamble strength is below the threshold, the inter-
frequency measurement is triggered.
Power offset Sd1: ready to trigger a HO when serving BTS preamble
strength is stronger than St
Power offset Sd2: ready to trigger a HO when serving BTS preamble
strength is below St
Sd1 and Sd2 is referred to as the power hysteresis
The large the power offset threshold is set, the smaller the possibility of
HO to be triggered
Filter coeff1: power smoothing coefficient when Ut is in stationary state
Filter coeff2: power smoothing coefficient when Ut is in mobile state
Time_to_Trigger: the number of times for power validation before the Ut
boost the HO procedure
EMS Parameter Configuration (HO)

92. 92McWiLL
LDB algorithm switch
The algorithm is disabled when the switch is set to NO
Only inter-frequency LDB is supported.
BTS Overload threshold
When the serving BTS’s load metric is larger than this threshold, the imbalance
detection is enabled in UT.
UT compares both the signal strength and the load of the cells in its active set
Time interval for neighboring BTS load exchange
BTS reports its load information to its neighbor list
The reporting of the load is periodic
Load offset threshold
If the following inequation stands and the Time_to_trigger is satisfied, a LDB HO will
be triggered.
(Serving BTS load - UT load) - (target BTS load + UT load) > load offset threshold
LDB HO Time-to-trigger threshold
Interval for Ut’s periodic LDB judgment
UT detects the load imbalance in a periodic manner
This parameter should be larger than the BTS load exchange interval
EMS Parameter Configuration (LDB)

93. 93McWiLL
L1 - report
UT periodically send its specific power, resource and radio channel status
information to BTS
PHY_report1 & PHY_report2 are sent with PUTCH
PHY_report1
PPC_avg
DOWN_SCH & UP_SCH
Powercap
L_opt_qam
PHY_report2
PREAMBLE_RSS
FREQ_OFFSET
DISTANCE
TCH_RSS
FORBID_TS_MASK
QAM64_FORBID
CI_MASK

94. 94McWiLL
Power control
Purpose
It balances the need for sufficient transmitted energy
per bit to achieve the required Quality-of-Service (QoS)
against the needs to minimize interference to other
users of the system and to maximize the battery life of
the mobile terminal
How to achieve
Power control has to adapt to the characteristics of the
radio propagation channel, including path loss,
shadowing and fast fading, as well as overcoming
interference from other users in neighbouring cells.

95. 95McWiLL
Power control
(a) power control
(b) rate control

96. 96McWiLL
Power control
Categories
Open-loop power control
Closed-loop power control
Uplink Outer-loop power control
Downlink Outer-loop power control
Uplink Inner-loop power control
Downlink Inner-loop power control

97. 97McWiLL
Power control
Power control works on specific channels
Physical sub
channel
Open loop Inner loop Outer loop No power
control
PBCH X
PRACH X
PRARCH X
PRCH X
PRRCH X
PDTCH X X
PUTCH X X

98. 98McWiLL
Open-loop power control
Open-loop power control sets a coarse operating point for the
transmission PSD by open-loop means, based on path-loss estimation.
PRCH,PRRCH,PRACH,PRARCH adopt open-loop power control
Where
- transmission power
- expected reception power
- path loss measured by UT,
PL = BtsTransmittedPower- CpeReceivedPower
Another constraint
PowerCap = BtsTransmittedPower – CpeReceivedPower +
BtsReceiveSensitivity-19dB ，
PowerCap is applied to constrain UT’s tx power to avoid the near-far effect
( ) ( ) ( )sent destP dbm L db P dbm= +
( )sentP dbm
( )destP dbm
( )L db

99. 99McWiLL
Closed-loop power control
Inner-loop power control
Receiver evaluates its received signal strength together with
the interference power, thus to generate a SNR estimation
SNR = Ps - Pn
Receiver compares the temporary SNR with the SNRtarget
provided by the outer-loop power control module, and
generates a TPC command, which will be sent to the
transmitter.
Transmitter adjust its tx power on the basis of its previous tx
power according to the received TPC command
arg
arg
1 ( )
( )
1 ( )
tpc t et
tpc
tpc t et
SNR n SNR
m n
SNR n SNR
×∆ <
= 
− ×∆ >
( 1) ( ) ( )tpcP n P n m n+ = +

100. 100McWiLL
BTS UT
Send PC_SS
Measure the received
CINR and compare
Inner-loop
Set CINRtar
100Hz
There is a loop
for each UT
Closed-loop power control
DL inner-loop power control

101. 101McWiLL
NodeB
Set SNR target
Send PC cmd
CNR &SNR measurement
Inner-loop
1500Hz
Closed-loop power control
UL inner-loop power control

102. 102McWiLL
Closed-loop power control
Outer-loop power control
Target SNR is determined with
- basic SNR
FM - fading margin
Fading margin is updated periodically
Where
SnrOutage is the demodulated SNR interrupt
threshold in a statistical period
thSNR
th baseSNR SNR FM= +
( ) ( 1)FM n FM n FM∆= − +
baseFM SNR SnrOutage∆ = −

103. 103McWiLL
Closed-loop power control
UL Outer-loop power control
BTS UT
Send PC-SS
Inner-loop
Set CINRtarget
Obtain stable PER
performance
Measure the received
CINR and compare
Outer-loop
Snr out and Fading margin
update
PER target
1-5Hz
100Hz
Outer-
loop
power
control
module

104. 104McWiLL
Closed-loop power control
DL Outer-loop power control
Bts
Set CINRtar
Send PC-SS
Measure CINR
and compare
Outer
-loop
Inner-loop
UT
UT outer-loop
PC module
DL inner-loop and outer-loop Power control
1-5Hz
100Hz

105. 105McWiLL
DL CI UL CI
BTS 1 BTS 2
Single direction interference Double direction interference
UT1 CI UT2 CI
BTS 1 BTS 2
Downlink
Interference
uplinkInterference
Spatial nulling of Smart Antenna is not able to resolve all kinds
of intra-frequency co-channel interference problems.
N equals one
UT 1
UT 2
UT 1 UT 2
downlink
Interference
uplink
Interference
uplink
Interference
downlink
Interference
DL CI UL CI DL CI UL CI DL CI UL CI
UT1 CI UT2 CI
Even Worse case!

106. 106McWiLL
How to recognize a paired terminal
N equals one

107. 107McWiLL
N equals one
EMS parameter setup