Wi-Fi Module
- Anoop Bowdery
WiFi is an important technology globally, serving homes, commercial hot spots, industry, and under-served areas. WiFi is a prominent technology within the Private Networks and Indoor space. In providing success to our users we have introduced our new Wi-Fi Module. Which will allow us to further add the latest 802.11 versions
What is Wi-Fi
Wi-Fi technology is based on the IEEE 802.11™ series of wireless connectivity standards which have revolutionized how we communicate and access information. Billions of Wi-Fi devices are in use worldwide today, dramatically impacting how individuals, businesses, governments, and societies interact. It is no exaggeration to say that the IEEE 802.11 series of standards has helped bring about inexpensive, equitable internet access globally. [1]
The different 802.11 versions and comparisons are seen in the figure below.
Each new standard and release of 802.11 tackles the challenges faced by previous versions to provide better QoS to the end users
As such we are seeing Wi-Fi 6 not only tackle challenges Wi-Fi faced but is converging to fit the user cases as specified by IMT-2020
With faster speeds, low latency, higher bandwidth energy saving and with better performance in high dense areas
Wi-Fi Module in SignalPro
This new Module covers:
Support for all 802.11 Standards
WiFi Access Points
BSSID Identification
WiFi Studies
BSSID Clash & Interference Studies
Neighbor Planning
Traffic Modeling
Access Point Placement
Automatic Frequency Planning
Supporting All Propagation Models
Indoor Support
WiFi Cell Edge
Per BSSID Study
Get Started
The user must be licensed to use the Wi-Fi Module
Once licensed the Wi-Fi features will be available for planning and design
To open the Wi-Fi Feature set:
Go to → Network Design/Analysis → Wi-Fi Networks
The options under the module are
System Details/Service area…
BSID Conflicts
Neighbor Lists
Automatic Frequency Planning
System Details/Service area…
This dialog allows the user to input the standard they require, the soft parameter settings and external files for analysis
When a particular System Profile is chosen from the drop-down list, the FFT size & channel
Bandwidth will be chosen automatically. You can also enter values for the Frame Duration and Cyclic Pref
Adaptive Modulation
The Adaptive Modulation drop-down list allows you to select an adaptive modulation table to use for WiMAX studies. To create an adaptive modulation table, go to RF Systems>Adaptive Modulation.
Permutation Zone Allocation
In this section you may also specify Uplink/Downlink ratio, and the percentage of each frame allocated to a specific permutation type (e.g. PUSC, FUSC). These parameters are used in addition to the details from the adaptive modulation table to find the results for the various traffic or data rate studies when they’re run.
Handoff
This section allows you to specify whether the system will determine handoff based on a specific Power ratio between the servers in question at the remote or on the Absolute level of received power for the current server. Once the correct option has been chosen, you can enter the values that will be used for the handoff study.
There is also a checkbox option to Model Power Control.
Channel Plan Template File Name
The channel plan template file must be specified in this dialog in order to assign channels to any sector specified as a WiMAX system type. This file describes the arrangement of channels within the system including center frequency, bandwidth, and so forth. To create a new channel plan template, go to Utilities>Create/Edit Channel Plan Template (.cpt) file.
Assign Colors to Channel Groups
When selecting a channel plan template , there is an option to modify the color that is displayed for each channel in the “.cpt” file. After a “.cpt” file has been chosen by the user, selecting the Assign Colors to Channel Groups button will open the Assign Channel Group Colors dialog box which allows choosing the channel colors. There is a Styles button in the Map Layers dialog for the “Transmitter/Base/Hub sites” layer that supports the option to display a user specified color for the channel that is assigned to that sector.
Service Area Boundary File
The service area boundary file may be in either the “BNA” or “MIF” format and should be a simple polygon describing the geographic area in which the system is being designed. This polygon file can be easily created using the Draw>Polygon option accessed from the main menu bar.
Measured Sector Interference File Name
Enter the name of the measured sector interference file if this feature is being used in lieu of calculated interference. For more details on this file, including creation and use, please see Appendix I, section I.12 – Measured Interference Matrix File.
BSSID Conflicts
The Basic Service Set (BSS) is the foundational building block of a Wi-Fi network. It represents a group of stations (devices) that communicate with each other wirelessly within a given coverage area. BSS mode defines how devices interact and communicate within this set. [2]
A BSS uses a single AP. This might not be enough because of two reasons:
Coverage: A single AP’s signal can’t cover an entire floor or building. You need multiple APs if you want wireless everywhere.
Bandwidth: An AP uses a single channel, and wireless is half-duplex. The more active wireless clients you have, the lower your throughput will be. This also depends on the data rates you support. A wireless client that sits on the border of your BSA might still be able to reach the AP, but can only use low data rates. A wireless client that sits close to the AP can use high data rates. The distant wireless client will claim more “airtime,” reducing bandwidth for everyone.
To create a larger wireless network, we use multiple APs and connect all of them to the wired network. The APs work together to create a large wireless network that spans an entire floor or building. The user only sees a single SSID, so they won’t notice whether we use one or multiple APs. Each AP uses a different BSSID, so behind the scenes, the wireless client sees multiple APs it can connect to. We call this topology with multiple APs, an Extended Service Set (ESS)
APs work together. For example, if you associate with one AP and you walk around the building, you won’t disconnect. The wireless client will automatically “jump” from one AP to another AP. We call this roaming. To make this a seamless experience, we need an overlap between APs.
Each AP offers its own BSS and uses a different channel to prevent interference between APs.
EDX allows the user to view any conflicts, unassigned BSSID and allowable conflict in the BSSID Conflict GUI
To allow a conflict the user should highlight the conflict and select the downward arrow to push into the allows conflicts
Further the user can alter all BSSIDs within this GUI and it will be changed in all the project
Neighbor Plan
The neighbor plan is used to build the neighbor list for the network which will become more prevalent with latter versions of Wi-Fi
Neighbors can be planned using a criteria, coverage and distance. Users can commit any plan they run.
Automatic Frequency Planning
With the traffic load calculated for each cell base station or sector, it is now possible to assign the channels to each sector to handle this traffic. If you have a small system, or a simple system layout, assigning channels can be done manually. If your system is large or complicated, the Automatic Frequency Planning (AFP) capabilities of the Wi-Fi Module can be used.
To access the Automatic Frequency Planning dialog box, from the main menu bar select
Network Design/Analysis>WiMAX Networks>Automatic Frequency Planning.
Several parameters are required to do a successful frequency plan. These are explained below:
C/I Ratio Objective
This parameter is only used for the Internal and External frequency planning options described in the AFP section below. When creating a frequency plan, the first step is to determine which sectors are geographically close enough (or “close enough” in radio propagation terms) to potentially cause interference to one another. The threshold of determining what constitutes interference for this purpose is set here.
Percent Interference Acceptance
When a frequency plan is created, it cannot perfectly assign the channels so that all the interference conflicts are resolved and all the traffic is accommodated. This parameter tells the program that the maximum percentage of a sector’s service area (i.e. the area where it is the strongest signal) which can be lost to interference is this percentage value. A typical value here is 5 or 10 %.
Use Measured Interference matrix file
Frequency assignments are normally done using interference that is calculated using the propagation model for each interfering sector. However if you have switch or drive test data that can define the interference for each sector, this can be used by choosing this option. The name and location of this file is entered in the Define System/Service Area window and selecting the Other System Parameters.
The measured interference data entered into this file must follow the format described below:
siteid_serv(1), num_intrf(1)
siteid_intrf(1), signal_level_ratio(1), std_dev(1)
siteid_intrf(2), signal_level_ratio(1), std_dev(1)
siteid_intrf(3), signal_level_ratio(1), std_dev(1)
.
.
siteid_intrf(num_intrf),signal_level_ratio(num_intrf),std_dev(num_intrf)
.
.
siteid_serv(num_serv), num_intrf(num_serv)
where:
siteid_serv – the site ID of the serving sector enclosed in single quotes (ex, ‘AAAA0001’)
num_intrf – the number of interfering sectors listed for this serving sector
siteid_intrf – the site ID of an interfering sector enclosed in single quotes
signal_level_ratio – the mean measured signal level ratio in dB between the interfering sector and the serving sector
std_dev – the standard deviation in dB of the signal level ratios assuming a normal distribution
num_serv – the number of serving sectors with information in this file Assign Control or Traffic channels
Deny Co/Adj channels at site
These two options allow you to restrict the assignment of adjacent channels and/or co-channels to sectors at the same base site. Typically co-channels are never assigned to different sectors at a site unless the channel re-use is one.
Minimum Channel Separation at Site
In some systems, even adjacent channels do not provide sufficient isolation between sectors. This value allows you to set the minimum channel spacing between channels assigned to sectors at the same base site. Zero is the default.
Traffic Source
The traffic source that determines system loading can be specified in this section. Either predicted or measured traffic can be selected. These traffic figures are drawn from the appropriate entry found in each transmitter sector’s Channel Grid window. The traffic value used for planning can be scaled up or down by entering a number other than 100% in the Percent of total traffic for planning box.
The desired Signal Level Threshold is set in the RF Systems > Mobile/Remote Unit parameters for the mobile/remote unit number/type that is selected for the AFP.
Assign Fixed Number of Channels
Normally the number of channels per sector is determined by the estimated traffic load at the sector.
If this information is not available this option allows you assign a fixed number of channels at each
sector.
Automatic Frequency Planning (AFP)
There are two methods of PCS/cellular automatic frequency planning (AFP) available in the Wi-Fi
Module: Internal and External.
Internal
When you select Internal, you will invoke EDX’s method for AFP. This method provides for
interference conflict resolution as well as balancing channels assigned to sectors to match traffic
demand.
When using Internal, the first step the program performs is to calculate a sector compatibility matrix. This is done only inside the service area as defined by the service area boundary file entry in the Wi-Fi System Details dialog box (Wi-Fi Networks>System details/Service area).
Inside this boundary, the program will calculate and define the service areas for each sector as those locations where that sector provides the strongest signal. Only those sectors whose signal exceeds the Required service threshold found in the selected Mobile/Remote Unit will be considered. Next it will look at the signal levels inside each sector’s service area and determine those which are strong enough that the C/(I+N) ratio objective is violated. It will track all those areas where this ratio is violated for each sector and the sectors that cause the interference. It will then calculate the degree of interference each of the other sectors causes by calculating the percent of interference locations as a function of the total service area for the victim sector.
Finally, based on the service area of each sector, it will determine the traffic load from the areas served by that sector and, using the GoS, calculate the number of voice channels needed at that sector using the Erlang B formula or in the case of packet-switched traffic the number of channels based on data/channel
The results of this processing are written to an ASCII data file called cellcmpx.dat. This is the basic data that the AFP optimization will use to do its work. The format of the cellcmpx.dat file is as follows
EDX cell sector AFP compatibility matrix
num_sectors cinr accept_intrf minutes_per_call blocking_prob
siteid_serv serv_area calls traffic num_chan_req num_chan_assigned
ky_lock
nchan(1) nchan(2) nchan(3) . . .
. . . . nchan(num_chan_assigned)
siteid_intrf(1) prcnt_intrf(1)
siteid_intrf(2) prcnt_intrf(2)
siteid_intrf(3) prcnt_intrf(3)
.
.
.
siteid_intrf(num_sectors-1) prcnt_intrf(num_sectors-1)
where:
EDX . . . - header line to identify the file
num_sectors – the number of sector with information in this file
cinr– the objective C/(I+N) ratio
accept_intrf – the percent of interference which can be accepted in a
sector service area
minutes_per_call – the average call duration in minutes
Blocking_prob – the percent blocking probability
Siteid_serv – the ID of the serving sector
Serv_area – the total area for this serving site square kilometers
calls - the number of calls per hour for this sector
traffic – the required traffic load for this sector
num_chan_req – the number of channels required to accommodate the traffic
given the GOS.
num_chan_assigned – the number of channels currently assigned to this
sector.
ky_lock – this equals 1 if the channel lock checkbox is checked on the
channel plan screen for this sector. These means the current assignments
for this sector are to remain unchanged.
nchan(1), nchan(2) . . . – the channel numbers currently assigned to this sector. If the channel assignments on this sector are locked, then the AFP algorithm must preserve this channel assignment list and protect it from interference during the AFP process.
siteid_intrf – the ID of the interfering sector
prcnt_intrf – the percent of the total serving sector service area that is interfered with by this interfering sector. This number is a relative indication of degree of conflict between the serving sector and this interfering sector.
With the information in this file, and the cell channel plan template showing the number of available channels, the EDX AFP algorithm is ready to do its work. Basically, it attempts to devise channel assignments for each sector so that the traffic demand is met while at the same time making channel assignments so that no same or adjacent channels are used between sectors that have conflicts. The basic technique it uses is called Simulated Annealing (SA), which is a combinatorial optimization process.
With SA, there are several parameters that are used to control the process. Typical values are:
number of cooling levels = 300
cooling level step multiplier = 0.85
number of iterations at each cooling level = 900
co-channel cost weighting coefficient = 1.00
adjacent channel cost weighting coefficient = 0.01
interference cost weighting coefficient = 1.00
demand cost weighting coefficient = 1.00
You can adjust these parameters if desired for your particular optimization. Depending on the number of sectors, and the parameter settings, this process could take from several minutes to several hours to complete. When completed, the program will return with a message asking you to accept or reject the channel plan that has been produced by the AFP process. The channel assignment results will be contained in an ASCII data file called chanplan.tmp. If accepted, the chanplan.tmp file is read by the EDX software and those channel assignments loaded into the channel plan dialog box data positions for each sector. From that point forward you are ready to begin coverage and interference studies with your new optimized channel assignment plan.
External
External basically gives you access to an external dynamic link library (DLL) which contains your own compiled and linked code for running the AFP. Before calling this routine, the Wi-Fi Module performs all the calculations to create the cellcmpx.dat file as described above. It then passes this file name and the other relevant file names to the external AFP routine. When this routine is completed, the channel assignment results are written to an ASCII file called chanplan.tmp from which the channel assignments are imported back into EDX SignalPro.
The details of how the parameters are passed to the external routine, and the required format for the resulting channel assignment file, are found in the comment statements in the sample ext_afp.for code included on the distribution CD. Appendix J also has for more information on using this and other external calculation DLL’s.
Traffic Planning
To specify traffic loading for the Wi-Fi sectors, select Network Design/Analysis>Traffic
Loading, which displays a dialog box where you can set both the traffic definitions (types of packet traffic, and their associated average data rates and activity percentages) as well as how the subscriber
devices are distributed in the Wi-Fi system.
Traffic Data Source
There are four traffic data sources, or distributions, which can be selected from the drop-down list:
Uniform Traffic Distribution. Uniform distribution in which the probability of traffic originating from a given place inside the cell system service boundary is assumed to be equal.
Traffic base on Land Use (Clutter) Database. If you select this traffic data source, the distribution of traffic will be weighted according to the land use or morphology category. Typical there will be more calls or data originating from urban areas than agricultural areas, for example. To use this option you must have specified a land use (clutter) database.
Traffic based on demographic database. If you select this option, the traffic will be weighted according to the population in a given region of your cell system service area. To use this option you must have specified a demographic database.
Traffic from traffic database. If you select this option, the traffic will be weighted according to actual traffic density valued in a traffic database in a given region of your cell system service area. The type of traffic to be calculated in the system is defined by the type of data stored in this database. If it is voice traffic the data will be expressed in milliErlangs. If it is packet data then the traffic will be in Kbps. To use this option you must have specified a traffic database.
Packet‐Switched Traffic Densities
Selecting this button opens the Packet-Switched Traffic Densities dialog box, where you can enter specific information about the traffic on your system. You will see a Service Name section where you can name up to five different user types that will be serviced by your system. These names can be anything, but are best chosen to indicate the type. Typical examples are “Web/e-mail”, “FTP”, “VOIP”, “Video”, etc. For each user type you can specify the density of each of the four possible traffic data sources listed above. For example, if you want to plan your system to accommodate 5 mobiles/square km, enter a 5 in the first column after the row where you have listed “VOIP”. A similar approach is used to plan for a certain number of users per 1000 population. To set user density levels for different land use categories as defined in your land use database, click on the button as indicated alongside the user type.
If you don’t have specific information on the number of users in given areas, you can instead choose to enter a single data traffic load in Mbps that represents average traffic for all user types that will be used in a sector service area. To do this, click on the radio button labeled Use single average traffic density for all services. The appropriate data entry fields will become active and you can then enter the desired values.
Wi-Fi Traffic Definitions
Selecting this button opens a Packet-Switched Traffic Definitions dialog box, where you enter the names of up to five different user types in the Service Name section which can be serviced by your system. For each of the five, you specify the details of the data rate separately for both the uplink and downlink.
The dialog box allows the user to define up to five different types of service types along with their Service Flow (typically UGS or BE, but rtPS, ntPS and ErtPS are also available drop-down list choices), average downlink and uplink data rates and activity percentages (only applicable for rtPS, ntPS or BE). If the Service Name is left blank, then the information associated with that column of data will not be used in traffic studies.
Running a Traffic Loading Study
Returning to the Traffic Loading dialog box, before running a traffic loading study, there are several other parameters that need to be set. The first is the Transmitter Group for which the traffic loading is to be calculated. Typically you will be calculating traffic for all cell base station sectors in your system, but if desired, you can create sub-groups of sectors and just calculate traffic loading for them.
The second parameter is the signal level threshold located in RF Systems>Mobile/Remote Unit, for the mobile unit you’re using for the study. This study always uses the first Mobile/Remote unit in the Mobile/Remote unit list.
The third is to set the Percent of total traffic to be carried by this group in the Traffic Loading dialog box. Normally this should be set to 100%. However, if you are designing an overlay system that is intended to handle only a portion of the overall traffic load, or you have a CDMA system in which the traffic load is shared among more than one CDMA carrier, you may want to set this to something less than 100%.
With these parameters set, click the Calculate average traffic load on each sector button. The program will proceed to calculate the service area of each sector (those areas where it is the most likely server). With the service areas known, it will use your selected traffic data source (uniform, land use, demographic, etc.) to determine the traffic load in the service area of each cell sector. Finally, it will translate the traffic load into the required number of radio traffic channels to achieve the specified Grade of Service (blocking percentage). A status window will be displayed as the program progresses through these calculations. When the calculations are finished, the results are written to a report called
sector_traffic_loading.txt that can be found in the \reports folder of your project directory. You can use the Utilities>System reports feature to view this or any other report file. The traffic loading information is also automatically attached to the data for each cell sector so that it appears in the “Predicted” value of the Sector Traffic section of the Wi-Fi Channels dialog box for each sector. The calculated number of radio traffic channels to achieve the specified GoS is also shown in this section of the Wi-Fi Channels dialog box. This dialog box is accessed by clicking the Channels/Traffic button in the Transmitter Site Details dialog box.
Transmitters/APs
To set up the transmitters or access points, go to. → Transmitter/Base/Hub/Router Site Details
Here the user should get up using the Wi-Fi system type, BSSID , MiMO (if used) and all antenna parameters
For MIMO settings go to the MIMO/Adaptive Antennas. Users can use a predefined settng or create a custom one to fit their network
Once ready to run studies, user will find all the studies under the Wi-Fi System in the Area Study Details under Study Group
For more information please contact support
References
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