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Wireless Network
Wireless Network：Wireless Local Area Network(WLAN)，several AP work together to provide a wider wireless coverage
编辑于2022-10-17 15:41:30- moblie co…
- 2023年9月7日 Lecture1
Investment，其Future contracts：提前定好买卖价格，后面不管涨了还是跌了，盈亏自负，涨了，卖家亏钱，买家赚钱，跌了，买家亏钱，卖家赚钱
- Business Model
Business Model：Customer Segmentation、Value Proposition、Customer Relations、Revenue Streams……
- Basic Cryptography 2
modern cryptography ，有Modern Symmetric Ciphers、Stream Ciphers、ChaCha20、BlockCipher...
Wireless Network
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- 2023年9月7日 Lecture1
Investment，其Future contracts：提前定好买卖价格，后面不管涨了还是跌了，盈亏自负，涨了，卖家亏钱，买家赚钱，跌了，买家亏钱，卖家赚钱
- Business Model
Business Model：Customer Segmentation、Value Proposition、Customer Relations、Revenue Streams……
- Basic Cryptography 2
modern cryptography ，有Modern Symmetric Ciphers、Stream Ciphers、ChaCha20、BlockCipher...
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Wire
Overview
Type of networking techinology
circuit switching (for wireless voice communication)
three phase
circuit establishment
information transfer
curcuit disconnect
advantage
circuit dedicate to the connection
Guarantee full bandwidth
Guarantee quality of service
disadvantage
Inefficient: circuit may not be fully used
need extra delay for enstablishment
packet switching (for wireless data communication)
working flow:
send packets into network one by one
router received, stored, and passed it to next router
receiver remove header and reassemble msg
advantage
higher link efficiency
adapt to different data-rate transmission
do not block calls
priority can be used
disadvantage
end-to-end packet delay can vary subtantially
each packet carries extra header information
more processing required at each node
Classification
Coverage area
short range wireless network
WPAN
connect various within a close area
WLAN
cover a building
operate on unlicensed spectrum for ISM(industrial,scientific,medical)
free of charge, no license need
global availability
most comman at frequency band is at 2.4GHz
other often used bands at 5GHz, 6GHz, and 60 GHz
long range wirless network
WWAN
WMAN(wireless Metropolitan Area Network)
Satellite Network
operate by companies
Infrastructured
infrastructure based wireless network
via hub e.g. cellular system, WLAN
ad hoc wireless network
single-hop
multi-hop
Wireless Personal Area Network(WPAN)
overview
def
around an individual person
connected wirelessly
Characteristics
short communication range
low power comsumption
low cost
Generally small size
mostly ad-hoc network
IrDA (infrared data association)
IrDA, an association creates standard
IrDA has as set of protocals
features
communication range up yo 1m
no interfered by radio signal
low power for communication
bidirectional communication
low data transmission rate
low cost
line-of-sight
interfered by sunlight and heat
Bluetooth
2.4GHz, short range(10-100m,ad-hoc network)
interconnected
features:
not line of sight
unlicensed ISM band
Low cost
use FHSS + TDD + TDMA
provide networking with piconet and scatternet
support voice and data with SCO and ACL links
standard for interoperability(通用性)
Frequency Hopping and Time Division Duplex
2.4 GHz ISM for communication
Frequency hopping
79 channel, 1MHz each,total 83.5Mhz
each channel divide into time slots, 625μs each (1600 hops/s)
TDD
adjacent time slot are allocated for communication
Piconet
composition:
1 master and 1~7 slaves
signal channel in a piconet that uses a unique FH pattern
Master determine the frequnecy hopping patttern
slaves sychronized to the master's FH pattern
Parked: do not have a connection but are known and can be reactivated
Standby: do not join the piconet
from a piconet
first device initiates the piconet become the master
master send its device ID (48 bits, unique worldwide, determined the FH pattern) and clock (determined the phase in FH pattern) to other.
one standby device adjust the internal clock to the master's
active ---> assigned a 3-bit active member address (AMA)
parked ---> 8-bits parked member address (PMA)
standby ---> no address
master and slave communicate alternatively
TDMA used to support multi slaves --> master
scatternet
multiple pico-net forms a scatter-net
some device play a dual roles at same time
Master and slave (M/S)
slave and slave (S/S)
no master and master (same piconet)
communication
S/S sychronized to different FH sequences
A M/S suspend its current piconet and sychronized to another piconet
SCO and ACL
Polling based TDD
Master poll slaves
slaves reply in adjacent slots
Sychronous Connection Oriented (SCO) link for voice
use asymmetrical two consecutive single slots periodically
Asychronous Connection-less link for data
use 1/3/5-slot for variable packet szies, asymmetric bandwidth
bluetooth protocal stack
radio
baseband
Link Management Protocal
Logical Link Control and Adaptation Protocal(L2CAP)
Service Discovery Protocol (SDP)
Higher layer protocols/apps
porfiles
basis for interoperability
vertical slice through the protocal stack
specified:
Generic access
Headset
Fax
File transfer
...
IEEE 802.15
overview
1999 ,standard for PANs and short distance wireless networks
aim at standardizing the MAC and Physical layer of the bluetooth
also deal with othe issue: coexistence and interoperability
805.15.1
based on Bluetooth and define the MAC and PHY laye specifications
805.15.2
coexistence of WPAN and WLAN operating in the same 2.4GHz band
805.15.3
standard for high rate WPANs(>=20Mbps)
provide means of low-power and low cost for portables
805.15.4
low data rate, long battery life, low complexity
targeted at sensors, interactive toys,....
805.15.5
standard for mesh networking
range extension, more robustness, longer battery life
805.15.6
standard for body area network
805.15.7
standard for freespace optical communication
805.15.8
standard for optimize p2p and infrastructureless communication below 11GHz
P805.15.9
transport of Key Management Protocol (KMP) datagram
P805.15.10
routing packets for dynamically change wireless network
Other WPAN technologies
Ultra Wideband (UWB)
for military radar systems
480Mbps (<3m ) or 11Mbps (<10m)
Wireless USB
for PC
<3m , 480Mbps
Z-Wave
for home automation
<30m, 127Kbps
Wireless Local Area Network(WLAN)
Overview
characteristic
very flexible
no wire
robust
save cost
high-speed internet access
Infrastructured network
Laptop 20m~100m linkded to AP (Access Point)
AP controls the access to the shared channel
several AP work together to provide a wider wireless coverage
Ad hoc network
no central controller
use MAC protocols (e.g. IEEE 802.11 uses CSMA/CA)
WLAN Standards
IEEE 802.11
infrastructured-based WLAN
Station(STA)
手机，电脑
Access Point(AP)
WiFi
Basic Service Set (BSS)
手机电脑和WiFi
using the same frequency band channel
Extended Service Set (ESS)
a set of BSS
Distribution System (DS)
connect APs in an ESS to form a logical network
Portal
Bridge to othe networks
Ad hoc WLAN
Independent Basic Service Set(IBSS)
a group of station using the same radio frequency
protocal architecture
802.11x
Medium Access Control (MAC)
MAC
access mechanisms,fragmentation,encryption
Physical layer (PHY)
PLCP Physical Layer Convergence Protocal
carrier sense--->clear channel accessment
PMD Physical Medium Dependent
Modulation, coding
Management
MAC management
sychronization
find a LAN, stay within a LAN, timer,etc.
sychronization using beacons
Infrastructure based
beacon interval
beacon frame
AP boardcast
AP information
Ad hoc based
beacon interval
beacon frame
Station boardcast
Station information
random delay
Association/Reassociation
new station integrate to a LAN
Roaming, change network by change AP
Scanning, active search for a network
scanning the environment
association / reassociation request
association / reassociation reponse
success: join the AP
AP signal a new station to the distributed system(DS)
DS update its data base
DS inform the old AP to release resource
fail: continue scanning
MIB, Management Information Base
manage read and write operation
power management
power saving mode without a missing a message
station mode:
continuous aware mode
Power saving mode (PSM)
infrastucture based
Traffic Indication Map (TIM)
AP announces a list of unicast receiver
Delivery Traffic Indication Map (DTIM)
AP announces a list of broadcast/multicast recevier
ad hoc based
Ad-hoc Traffic Indication Map(ATIM)
PHY management
channel selection, MIB
Station management
coordination of all management functions
Physical layer
frequency:
2.4 GHz (802.11b/g) (majority)
14 channel range spaced 5 MHz apart
22MHz/ channel
center point: 2412 , 2417 , 2422 , ... , 2482MHz
Adjacent channels overlap ---> using FHSS/DSSS/OFDM
5GHz (802.11a/h)
center point = 5000 + 5 * channel number (MHz)
16.6MHz/channel
MAC Layer
Distributed Coordination Function (DCF)
default
transmit data packet on "best effort"
support boardcast
Point Coordination Function ( PCF)
optional
transmit data on periodic polling strategy
Interframe space (for priority)
SIFS (Short Inter Frame Space)
highest priority
used for ACK, CTS, polling response packets
PIFS (PCF IFS)
medium priority
used for PCF
DIFS (DCF IFS)
lowest priority
used for DCF
Access methods
DCF CSMA/CA
CA and random back-off time
ACK packets
workflow:
Boardcast:
carrier sense, for DIFS then send data
medium busy, wait for a free DIFS, then random backoff time(multiple time slots), then send
if occupy during backoff time, backoff timer stop, wait fro another chance
Unicast
wait for DIFS, send data
received correctly, then receiver wait for SIFS, then send ACK packets
transmission error --> sender retransmit later.
DCF with RTS/CTS
avoid hidden terminal
workflow:
sender wait for DIFS, then send RTS and reserve parameter( amount of time that finish transmission)
Recevier wait for SIFS, reponses CTS
sender wait for SIFS, then send data
receiver wait for SIFS, then send ACK
other station defer to access the medium for a period of time define by NAV
PCF
AP polls terminal according to a list
workflow
contention free period
PCF
contention period
DCF
history
802.11 (1997, outdated)
2.4 GHz range bandwidth with data rate of 1 or 2 Mbps
802.11b (Wi-Fi – Wireless Fidelity, 1999)
The 2.4 GHz ISM band
Specify a PHY layer providing a basic rate of 11 Mbps
802.11a (1999)
Provide data rates up to 54 Mbps at 5 GHz band
802.11g (2003)
Compatible with 802.11b, higher data rate (54 Mbps at 2.4 GHz band)
802.11n (2009)
Backward compatible with 802.11b/g at both 2.4 GHz and 5 GHz bands, theoretical data rate of 600 Mbps and transmission range of 50 meters by using MIMO
802.11ac (2013)
Extend the air interface embraced by 802.11n to provide over 1Gbps for multi-station WLAN throughput and at least 500 Mbps for a single link throughput (at 2.4 GHz and 5 GHz bands)
802.11ad (2013)
To provide a WiGig network standard at 60 GHz millimeter wave (mmW) frequency networks
Limited communication range (a few meters), high data rates (up to multiple Gbps)
802.11ax (2019)
The successor to 802.11ac that provides high efficiency of the throughput per-area (compared to 802.11ac) by means of OFDMA (at 2.4 GHz, 5 GHz, and 6 GHz bands)
802.11be (2021)
Built upon 802.11ax, focusing on WLAN indoor and outdoor operation with stationary and pedestrian speeds in the 2.4 GHz, 5 GHz, and 6 GHz bands.
Other 802.11 standards
IEEE 802.11e – enhancing MAC to provide QoS for multimedia app.
IEEE 802.11h – enhancing PHY of 802.11a for compliant with Europe
IEEE 802.11i – enhancing MAC to increase security
IEEE 802.11k – radio resource measurement enhancement
IEEE 802.11p – wireless access for the vehicular environment (WAVE)
ETSI HiperLAN
Radio LANs standard developed in Europe by ETSI
for MAC and PHY layer
operate in 5.15GHz and 17.1GHz
50m coverage
special design for ad hoc computing
standard
HiperLAN/1 Indoor ~20Mbps
HiperLAN/2 Indoor boardband multimedia ~50Mbps
Wireless Wide Area Network(WWAN)
cellular network
basic
divide sthe sapce into cells
cell size 300m~40Km
highly polulated area ----> Microcell ---->base station placed closed to each other
cell can be partitioned into sectors , each antenna serves a sector
frequency reuse
each base station is assigned a group of radio channels
neighboring cells are assigned different channel groups
reuse the channel groups if the interference level is below tolerable thresholds
Key components
MS moblie station
hardware,
software,
Subscriber identity module (SIM) which store the user profile
BS base station
hardware
BTS base transceiver station
sender,
receiver,
antennas
BSC base station controller
switching between BTSs,
controlling BTSs,
managing radio channel
channels
control channel
exchange ctrl information
traffic channel
deliver voice and data
Moblie switching center(MSC)
managing a group of BSs, ctrl all the connection within its domain
set up connection,
route traffic,
gateway to external network
LR Location Register
usage
authenticate MS
manage location information of MS
home location register HLR
keep user's profile
moblie device ID
autentication keys
location
visitor location register VLR
subset of MS's user profile
basic operation
initialization
MS scan BSs's beacon signal in the set up ctrl channel
associate with the BS with strongest signal
MS register to the MSC via teh associated BS
MS updates its location information to HLR and VLR
sender has a call
sender find its channel is idel, send a call request with the receiver's phone number to the MSC
the call request will b blocked if free channel is not avaliable
MSC pages the receiver
MSC ends a paging msg within certain cells where the recevier may lcocate via their BSs, The paging msg contain the receiver's phone number
Each BS sends the paging msg within its cell
The recevier receive the paging msg and recognized the phone number
the receiver reponses to the BS and BS reponse to the MSC
Call is accept
When the receiver responses to MSC’s paging message, MSC setups a connection between two BSs, finds free traffic channels within each BS, and notifies each BS; BSs then notify both sender and receiver
An end-to-end connection between sender and receiver is established
2 MSs having a call
Two MSs (sender and receiver) exchange voice signals via the established connection through BSs and MSC
Call is complete
One MS (sender or receiver) terminates the call
MSC is informed the call completion
MSC releases the assigned traffic channel
history
1G (1980s)
Analog networks
Channel bandwidth (date rate): 2kbps
Multiplexing: FDMA
Service: voice communication
Switching: circuit switching
Core network: PSTN
2G (1990s)
system
Digital AMPS (DAMPS): known as TDMA in Americas
GSM (Global System for Mobile Comm.): most popular 2G
CDMA (CDMA IS-95 / cdmaOne): introduced by QUALCOMM
PDC (Personal Digital Cellular): used in Japan, based on TDMA
Digital networks
Channel bandwidth (date rate): 64kbps
Multiplexing: TDMA/CDMA
Service:
digital voice,
voice mail,
call waiting,
SMS/MMS
Switching: circuit switching, packet switching (option)
Core network: PSTN
2.5/2.75G
system
GPRS (General Packet Radio Services) – 2.5G
CDMA2000 1x – 2.5G
EDGE (Enhanced Data rates for GSM Evolution) – 2.75G
Channel bandwidth (date rate): up to 144kbps
Multiplexing: CDMA
Service: SMS/MMS, high capacity packetized data
Switching: packet switching
Core network: PSTN
3G (2000s)
system
CDMA2000 1x EVDO and EVDV in America
UMTS (Universal Mobile Telecommunication System) in Europe
WCDMA (Wideband CDMA) -- air-interface of UMTS
Channel bandwidth (date rate): 144 Kbps to 2M bps
High mobility (speed >= 120 KM per hour) - 144Kbps
Full mobility (speed < 120 KM per hour) - 384Kbps
Limited mobility (speed < 10 KM per hour) - 2Mbps
Multiplexing: CDMA
Service: enhanced quality of service audio/video/data
Switching: packet switching
Core network: packet network
3.5G
system
HSPA (High Speed Packet Access)
HSPA+ (Evolved HSPA)
Channel bandwidth (date rate): more than 2M bps
Multiplexing: CDMA
Service: integrated high quality audio/video/data
Switching: all packet
Core network: Internet
4G (2010s)
major technology
LTE(Long Term Evolution) Andvanced standardized by 3GPP
LTE is branded "4G", but the first LTE release does not fully comply with the requirements of 4G standards (Pre 4G).
LTE Advanced, as an enhancement to LTE, aims to reach and surpass the requirements of 1 Gbps for stationary reception and 100 Mbps for mobile reception.
802.16m standardized by the IEEE
Mobile WiMAX (IEEE 802.16e) standard is also branded “4G”, yet its peak date rate does not reach the requirements of 4G.
802.16m (WirelessMAN-Advanced) is the evolution of 802.16e, with the objective to fulfill the criteria of 4G
All-IP packet switched network
Provide wide bandwidth for high data rates multimedia services
100Mbps for high mobility
1Gbps for low mobility
Guaranteed QoS, suitable for high quality multimedia
Ubiquitous connection and seamless handovers among heterogeneous network
Provide customized services
5G (2020s)
main app wireless world wide web(WWWW)
3 main type services
enhanced moblie broadband (eMBB)
Ultra-reliable low-latency communication (URLLC) for mission-critical app
Massive machine-type communication (mMTC)
5G requirements
Peak data rate: 20Gbps downlink and 10Gbps uplink per mobile BS.
Real-word data rate: user download speeds of 100Mbps and upload speeds of 50Mbps.
Latency: less than 4ms for end-to-end latency
Spectral efficiency: 30bits/Hz for downlink and 15bits/Hz for uplink
Mobility: support movement from 0 to 310mph
Connection density: support 1 million connected devices per km2
5G standards
3GPP chose the 5G NR (New Radio) standard together with LTE as their proposal submitted to the IMT-2020 standard.
5G NR is the global standard for the new air interface for 5G networks.
5G NR includes lower frequencies (FR1, below 6 GHz) and higher frequencies (FR2, above 24 GHz).
3GPP chose evolution of NB-IoT and eMTC (LTE-M) as 5G technologies for the LPWA (Low Power Wide Area) use case for Internet of Things.
5G features
Unified platform
Not only elevate mobile broadband experiences, but also support new services such as mission-critical communications and the massive IoT
Support all spectrum types (licensed, shared, unlicensed) and frequency bands (low, mid, high)
Support a wide range of accesses, such as macro-cells, hotspots, and interconnect (device-to-device and multi-hop mesh)
Wide use of spectrum
Use spectrum across a wide spectrum — from low bands (< 1 GHz), to mid bands (from 1 GHz to 6 GHz), to high bands (millimeter-wave)
Faster
Have up to 20 Gbps peak data rate and 100+ Mbps average data rate
More capacity
Support a 100x increase in traffic capacity and network efficiency
Low latency
Have significantly lower latency: a 10x decrease in end-to-end latency down to 1ms
Satellite
overview:
provide network for whole planet
no need for roam
transponder
peak data rate 2.4lbps~2Mbps
receive on one frequency band , amplify the signal intenisty and transmit signal on another frequency band
usage
oil and gas industry, military bases, oceans
search and rescue
Radio and TV boardcast
Weather satellites
satellite navigation
GPS
GLONASS
BeiDou
Galileo
types
Geostationary Earth Orbit(GEO)
36,000km
Medium earth Orbit (MEO)
6,000km~20,000km
Low Earth Orbit(LEO)
500km~1,500km