WiFi Device Performance

Device design does not end with the device. Determining a good design means knowing that it will work well in all of its intended environments. With indoor WiFi environments, the metrics for a good design include received power, multipath, complex impulse response, throughput, capacity, and more.

Figure 1: Far field gain pattern of an inverted FL antenna in a laptop simulated using XFdtd

XFdtd and Wireless InSite ensure a comprehensive WiFi device design process, from simulating the initial antenna pattern to indoor modeling to determine optimal coverage. Together the products can ensure accurate simulations and a smooth workflow. 

Indoor Scenario Design Example

In this example, we have taken an inverted FL antenna and placed it into a laptop. The antenna is simulated in XFdtd to output the far-field gain pattern.

An apartment environment is created using Wireless InSite’s floor plan editor and furniture is placed using imported CAD objects. Two transmitters are placed on the ceiling and the entertainment center as the WiFi access point. The receivers are mounted 1.5m above the floor in several locations, both within line-of-sight, and beyond-line-of-site from the transmitter.

The three-room apartment with door openings and windows contains common household objects like a couch, TV, dining table, etc. This custom scenario built using Wireless InSite allows users to specify their scene as desired. Similar scenes such as a conference room, warehouse, multi-story house or building can also be simulated.

Wireless InSite supports XF’s radiation patterns as input that can be assigned to a transmitter and/or receiver. For the apartment, we consider the inverted FL antenna as the receiver and short monopole antenna at 2.4 GHz as the transmitter. Each receiver is assigned with the far-field pattern that we imported from XF, while the short monopole is created within Wireless InSite.

Figure 2: Custom apartment scene with transmitters placed on ceiling and entertainment center

Figure 3: Imported far-field gain of the inverted FL antenna simulated using XFdtd

Wireless InSite’s study area properties allow users to configure and control various aspects of the physics and ray-tracing calculations. Figure 4 shows the study area setup dialogue for the X3D Propagation Model. The study area is defined to use Wireless InSite’s GPU-accelerated X3D ray model, with ray-tracing defined to include propagation paths with up to six reflections and one diffraction, omitting transmissions to limit calculations to the outdoors.

Simulations using the single Tx antenna and a MIMO antenna are performed. Wireless InSite provides user-requested outputs such as received power, propagation paths, time of arrival/departure, etc. A typical result from the analysis of a single transmitting antenna is the power received by a laptop antenna in the form of a coverage map over an area. Figure 5a and 5b provides a field map showing the coverage in the vicinity of the access point.

Figure 4: The Study Area Properties window gives users control over which propagation model to run and the number of interactions along with atmosphere and Monte Carlo statistics

Figure 5a: Field map showing the coverage from the Ceiling Tx over an area of the apartment

Figure 5b: Propagation Paths from Tx to Rx in the apartment


Communication Systems Analyzer

Wireless InSite’s ray-tracing propagation models produce received power and path data through which the Communication Systems Analyzer outputs device performance matrices. This includes Bit Error Rate (BER), throughput, capacity, and combined outputs from multiple transmitters. The post-processing ability can be expanded to multiple configurations of the system.

 WiFi modulation and coding scheme (MCS) and BER are available for WiFi protocol at various SNR levels. For WiFi 802.11n and 802.11ac, each MCS has an associated throughput based on the SNR. The UE receiver threshold is needed as well.

Read more about the Communication System Analyzer...

Figure 6: Throughput for laptop Rx from a 802.11ac Tx calculated according to the noise power density and signal bandwidth

Figure 7: Communication System Properties window with parameters to calculate BER, throughput and interference

Additional Information


WiFi Performance in a House with Two Routers

The following example investigates WiFi throughput coverage in a house provided by 802.11ac routers operating at 5 GHz using an 80 MHz bandwidth. The geometry for the house was imported from a CAD file and a flat terrain was placed underneath the house.