Cross Layer Optimization
link 1
link 2
This concept is going to be important from the perspective of developing a cognitive and adaptive WiMAX radio. The use of MIMO and other advanced antenna technologies are going to enhance the PHY layer significnatly. From a simulation perspective a cross layer approach is going to be required in order really show the true performance. the MAC layer side of the system needs to be incorporated with the advanced PHY layer.
There is research in the area of developing better simulations in order ot address the cross layer issues.
Definitely need to consider some of this with regards to cognitive WiMAX
Friday, November 30, 2007
Wednesday, November 14, 2007
dedicated pilots / MIMO WiMAX beamforming
http://www.home.agilent.com/agilent/editorial.jspx?action=download&cc=US&lc=eng&ckey=1213544&nid=-536902344.536910932.00&id=1213544
WiMAX plug fest architecture/test plan
http://www.wimaxforum.org/technology/downloads/2nd_Mobile_WiMAX_PlugFest_White_Paper.pdf
Tuesday, November 13, 2007
knobs for cognitive radio
Radio paramters
transmitter power, frequency, bandwidth, modulation, and channel
coding
FroM Rieser PhD Thesis
0 Power
1 Carrier Frequency (Fc)
2 Bandwidth
3 Symbol Rate
4 Modulation
5 Forward Error Correction (FEC)
6 Payload/frame length
7 Automatic Repeat Request (ARQ)
8 Dynamic Range
9 Equalization
10 Encryption
11 Antenna Configuration
12 Voice
13 Noise Cancellation (limiting)
14 Interference Temperature
15 Time Division Duplex (TDD)
transmitter power, frequency, bandwidth, modulation, and channel
coding
FroM Rieser PhD Thesis
0 Power
1 Carrier Frequency (Fc)
2 Bandwidth
3 Symbol Rate
4 Modulation
5 Forward Error Correction (FEC)
6 Payload/frame length
7 Automatic Repeat Request (ARQ)
8 Dynamic Range
9 Equalization
10 Encryption
11 Antenna Configuration
12 Voice
13 Noise Cancellation (limiting)
14 Interference Temperature
15 Time Division Duplex (TDD)
Sunday, November 11, 2007
Conflict between 802.16h and 802.22
802.16h was originally intended for coexistence of WiMAX in unlicensed bands.
see article at wifi planet detailing some of the tension between 802.16h and 802.22
They ammended the scope of the PAR to include coexistence with primary users. in addition to the coexistence with self. This is a huge issue as it directly places 802.16h in tension with 802.22. This places overlap in their scopes. If 802.16h can expand into the TV bands then 802.16h is essentially the same thing as 802.22
This letter shows the response from 802.16h to a letter from 802.22 about overlap in their scopes.
see article at wifi planet detailing some of the tension between 802.16h and 802.22
They ammended the scope of the PAR to include coexistence with primary users. in addition to the coexistence with self. This is a huge issue as it directly places 802.16h in tension with 802.22. This places overlap in their scopes. If 802.16h can expand into the TV bands then 802.16h is essentially the same thing as 802.22
This letter shows the response from 802.16h to a letter from 802.22 about overlap in their scopes.
Periodization from Sports Physiology applied to cognitive radio
In perodized training, the phsyical development is broken down into specific periods. Each period builds on the last period and leads into the next one. The ultimate goal is to be that fittest for the most important races. This means that during the earlier periods, peformance will be degraded in order to develop fitness. Performance is sacrificed in the earlier periods so that they will be in the best condition during the racing period.
How can this be applied to cognitive radio.
Develop specific periods. In some periods actual performance is not very good. But congitive abilites are higher. Sacrifice performance in order to learn more about the current environment. While learning the radio can't perform as well as it could, but it is developing the ability to perform better latter on.
Later on, switch to a new period where performance is maximized. In this period the radios cognitive abilities are somewhat dimished in order to increase it's ability to perform.
For example, if there is no important data to send at the moment switch to a low performance/high cognitive period. Higher overhead and lower performance but is ina learning state where the knowledge gained can be of use when needed.
When higher priority data is required switch to a new phase of operation.
So rather than be in the same state all the time, change operation modes in order to maximize capabilities when they are needed
articles
one
wiki
How can this be applied to cognitive radio.
Develop specific periods. In some periods actual performance is not very good. But congitive abilites are higher. Sacrifice performance in order to learn more about the current environment. While learning the radio can't perform as well as it could, but it is developing the ability to perform better latter on.
Later on, switch to a new period where performance is maximized. In this period the radios cognitive abilities are somewhat dimished in order to increase it's ability to perform.
For example, if there is no important data to send at the moment switch to a low performance/high cognitive period. Higher overhead and lower performance but is ina learning state where the knowledge gained can be of use when needed.
When higher priority data is required switch to a new phase of operation.
So rather than be in the same state all the time, change operation modes in order to maximize capabilities when they are needed
articles
one
wiki
WiMAX applications to transportaion
Pt-to Pt and/or Pt to Multipoint links to support ITS devices in the field
-Sensors
-DMS
-Cameras, IP video
- VOIP to field personnel
- construction monitoring
- infrastructure monitoring
- any other ITS requiring comm
-higher bandwidth backhaul for local DSRC
DOTS looking into it
SCDOT
PENN DOT
AZ DOT
NY DOT
FL DOT
Long range, potential NLOS capabilities
high quality of service that lends itself to applciaitons such as video. Scheduled Downlink/uplinks and not CSMA
Mobile WiMAX, vehicle to roadside
-vehicle to vehicle comme through a base station
-VII applications, Weather sensing using information from individual vehicles
Coexistence issues between DSRC and WiMAX
potentially similar spectrum
QOS for multimedia delivery
Deployment scenarios for a DOT
-camera specific / ITS designs
License requirements
-4.9 usage for public safety
-Sensors
-DMS
-Cameras, IP video
- VOIP to field personnel
- construction monitoring
- infrastructure monitoring
- any other ITS requiring comm
-higher bandwidth backhaul for local DSRC
DOTS looking into it
SCDOT
PENN DOT
AZ DOT
NY DOT
FL DOT
Long range, potential NLOS capabilities
high quality of service that lends itself to applciaitons such as video. Scheduled Downlink/uplinks and not CSMA
Mobile WiMAX, vehicle to roadside
-vehicle to vehicle comme through a base station
-VII applications, Weather sensing using information from individual vehicles
Coexistence issues between DSRC and WiMAX
potentially similar spectrum
QOS for multimedia delivery
Deployment scenarios for a DOT
-camera specific / ITS designs
License requirements
-4.9 usage for public safety
802.22 vs Cognitive WiMAX
802.22 is planning on using an OFDM structure similar to 802.16. 802.22 is being designed specifically as a cognitive technology due to the requirement of coexistence between units and the need to not interfere with incumbents (television, wireless microphones)
Besides the frequency being used, what would the difference be between a fully cognitive 802.16 and 802.22. I guess the requirement to not defer to an incumbent
Besides the frequency being used, what would the difference be between a fully cognitive 802.16 and 802.22. I guess the requirement to not defer to an incumbent
thoughts on coexistance cognitive WiMAX
802.16h focused only on coexistence of WiMAX in the unlicensed bands. It is not really a fully cognitive application.
Berleman paper talked about techiques for how 802.16 can block out competing 802.11 radios in the same spectrum. Because of 802.11's reliance on listen-before-talk MAC the WiMAX is able to block out 802.11 as needed by making it's tranmissions longer than the contention period for 802.11. This in effect does not allow the 802.11 to transmit when the 802.16 wants to. Of course this is a totally unfair type of methodology.
Possible similarilty between 802.16 coexistence and 802.11e in terms o fthe hybrid controller and sharing a single frequency channel in the time domain.
802.22 will use coexistence beacons to help with self coexistence of multiple Base Stations in the same area.
-Coexistence beacons will be time stamped, CPE from neighboring networks may be able to overhear the beacons. They will be looking for them to be able to help inform their own basestations of potential hidden nodes that the base might not be able to see
Currently a WimAX deployment requires significant planning for frequency reuse strategies. The Base station coordiantion of large scale deployments is similar to cell phone type deployments. While this is an acceptable and almost required deployment strategy for North America what about in highly rural and depressed 3rd world countries. Or in areas where countries are bordering with each other.
It is highly unlikely that you are going to be able to enable such a strong coordination between base stations. More likely is that you are going to have people just setting these up without knowledge of the other Base stations in the area. Licenses may be granted for a particular area by a country but these will be invalid when you are on the border of another country.
Cognitive WiMAX would lend itself to an automated initialization sequence upon powering up. This enables a low level of skill to be required for the design and deployment of a network which lends itself to a 3rd world type deployment. A base station and accompanying CPEs would be able to start up and sense the environment in terms of frequency availability and potential interference. based on this knowledge it can change it's PHY setup to accomadate the current environment.
Question, if a Base station is constantly sensing and decides to change frequencies than it will have to tell all the CPEs but what happens if a new CPE turns on but doesn't know what frequency the Base is on. In current WiMAX the frequency is fixed and the CPE knows where it needs to be to find the base station. In this type of case, the CPE is going to have to go through a search mechanism for scanning the potential frequencies that a base station would be on until it finds it.
Current WiMAX is a narrow profile compared to what the 802.16 standard is capable. This was required to develop synergy among vendors and to solidify a development plan and create more economy of scale for the development of WiMAX.
A cognitive WiMAX would be a very flexible radio, capable of changing its frequency, power and range, and other variables to accomadate the desired operation and the wireless ecosystem in its surrounding area.
The 802.16 MAC structure has an inherent weakness in that it is based of a scheduling system coordinate by the base station. there is no listen than talk of like 802.11. The WiMAX will provide higher quality of service and more efficient bandwidth but if there is enough noise or interference to block the preamble and the DL/UL scheduling there might be problems.
frame based 802.16 MAC requires significant rigourous protection
Berleman paper talked about techiques for how 802.16 can block out competing 802.11 radios in the same spectrum. Because of 802.11's reliance on listen-before-talk MAC the WiMAX is able to block out 802.11 as needed by making it's tranmissions longer than the contention period for 802.11. This in effect does not allow the 802.11 to transmit when the 802.16 wants to. Of course this is a totally unfair type of methodology.
Possible similarilty between 802.16 coexistence and 802.11e in terms o fthe hybrid controller and sharing a single frequency channel in the time domain.
802.22 will use coexistence beacons to help with self coexistence of multiple Base Stations in the same area.
-Coexistence beacons will be time stamped, CPE from neighboring networks may be able to overhear the beacons. They will be looking for them to be able to help inform their own basestations of potential hidden nodes that the base might not be able to see
Currently a WimAX deployment requires significant planning for frequency reuse strategies. The Base station coordiantion of large scale deployments is similar to cell phone type deployments. While this is an acceptable and almost required deployment strategy for North America what about in highly rural and depressed 3rd world countries. Or in areas where countries are bordering with each other.
It is highly unlikely that you are going to be able to enable such a strong coordination between base stations. More likely is that you are going to have people just setting these up without knowledge of the other Base stations in the area. Licenses may be granted for a particular area by a country but these will be invalid when you are on the border of another country.
Cognitive WiMAX would lend itself to an automated initialization sequence upon powering up. This enables a low level of skill to be required for the design and deployment of a network which lends itself to a 3rd world type deployment. A base station and accompanying CPEs would be able to start up and sense the environment in terms of frequency availability and potential interference. based on this knowledge it can change it's PHY setup to accomadate the current environment.
Question, if a Base station is constantly sensing and decides to change frequencies than it will have to tell all the CPEs but what happens if a new CPE turns on but doesn't know what frequency the Base is on. In current WiMAX the frequency is fixed and the CPE knows where it needs to be to find the base station. In this type of case, the CPE is going to have to go through a search mechanism for scanning the potential frequencies that a base station would be on until it finds it.
Current WiMAX is a narrow profile compared to what the 802.16 standard is capable. This was required to develop synergy among vendors and to solidify a development plan and create more economy of scale for the development of WiMAX.
A cognitive WiMAX would be a very flexible radio, capable of changing its frequency, power and range, and other variables to accomadate the desired operation and the wireless ecosystem in its surrounding area.
The 802.16 MAC structure has an inherent weakness in that it is based of a scheduling system coordinate by the base station. there is no listen than talk of like 802.11. The WiMAX will provide higher quality of service and more efficient bandwidth but if there is enough noise or interference to block the preamble and the DL/UL scheduling there might be problems.
frame based 802.16 MAC requires significant rigourous protection
Study plan for understanding WiMAX
OFDM
-Frame structure
-preamble, FCH, DL, UL Mapping
OFDMA
QOS definitions
-Service flows
-UGS
-rPTS
-ErPTS
nrtPS
BE
MAC scheduling
TDD vs FDD
TDD is currently preferred, all WiMAX profiles right now are using TDD, all the mobile allplications will use TDD
Fast Feedback
UL ranging
AMC
Cyclic prefix
HARQ vs ARQ
Modulations Schemes
-QPSK
-16 QAM
- 64QAM
Convultoin Code (CC) vs Convultion Turbo Code (CTC)
Block Turbo Code
Low density Parity Check
MAC Layer fundamentals
-Docsis cable modem standard
Mobility/Handoff schemese
-Hard Handoff HHO
-Fast Base station Switching (FBSS)
-Macro Diversity Handoff
-Security
-EAP
- AES, CMAC
-3 way handshake
Smart Antennas
-Beam forming
-STC
-Spatial Multiplexing
-MIMO
-Alamouti STC, USM
-Collaborative SM
Frequency Reuse techniques
-Multicast Broadcast service
-MAP
-Media Access Protcol
-Cyclic Shif Transmit Diversity
CDF
Submap Burst structures
1xEVDV evaluation methodology
Definition of spectral Efficiency
Standards Evolution
Phy / MAC development at IEEE level vs WiMAX profile
WiMAX Network Reference Model (NRM
-MS, ASn, CSN
Reality, Relevance of WiMAX
-Last mile solution
-MANd
Intel's push
-low cost CPE
Momentum of WiMAX forum
-similar model, historic path of WiFI
Global / Rural implications
-Broadband to 3rd world
rural broadband to VA and other parts of USA
Fixed WiMAX vs other fixed backhaul solutions
Mobile WiMAX vs 3 G cellular
vs future technologies 802.22, 802.20
-Frame structure
-preamble, FCH, DL, UL Mapping
OFDMA
QOS definitions
-Service flows
-UGS
-rPTS
-ErPTS
nrtPS
BE
MAC scheduling
TDD vs FDD
TDD is currently preferred, all WiMAX profiles right now are using TDD, all the mobile allplications will use TDD
Fast Feedback
UL ranging
AMC
Cyclic prefix
HARQ vs ARQ
Modulations Schemes
-QPSK
-16 QAM
- 64QAM
Convultoin Code (CC) vs Convultion Turbo Code (CTC)
Block Turbo Code
Low density Parity Check
MAC Layer fundamentals
-Docsis cable modem standard
Mobility/Handoff schemese
-Hard Handoff HHO
-Fast Base station Switching (FBSS)
-Macro Diversity Handoff
-Security
-EAP
- AES, CMAC
-3 way handshake
Smart Antennas
-Beam forming
-STC
-Spatial Multiplexing
-MIMO
-Alamouti STC, USM
-Collaborative SM
Frequency Reuse techniques
-Multicast Broadcast service
-MAP
-Media Access Protcol
-Cyclic Shif Transmit Diversity
CDF
Submap Burst structures
1xEVDV evaluation methodology
Definition of spectral Efficiency
Standards Evolution
Phy / MAC development at IEEE level vs WiMAX profile
WiMAX Network Reference Model (NRM
-MS, ASn, CSN
Reality, Relevance of WiMAX
-Last mile solution
-MANd
Intel's push
-low cost CPE
Momentum of WiMAX forum
-similar model, historic path of WiFI
Global / Rural implications
-Broadband to 3rd world
rural broadband to VA and other parts of USA
Fixed WiMAX vs other fixed backhaul solutions
Mobile WiMAX vs 3 G cellular
vs future technologies 802.22, 802.20
Subscribe to:
Posts (Atom)