The Wifi Offload Gateway Test Case
The Wifi Offload Gateway Nodal test case is used the test the Wifi-Offload Gateway (WOGW). The test case emulates an Access Point carrying UE data. The Access Point supports a WLAN interface to the GW and also provides you with an option to include a Management Interface to the GW.
With this test case, you define:
The network environment, WAN Node, including optional Management Node, AAA Distribution Mode, Authentication and Accounting SUTs
Mobility Types:
Inter-SSID mobility between SSIDs. This mobility includes DHCP messaging.
Inter-AP mobility between the Access Points. The data messages from the UE go through a different Access Point and is seamless mobility.
Number of Mobile Subscribers, Activation/Deactivation rates, and Mobile UE authentication options (AAA Distribution Mode, Authentication and Accounting SUTs)
CAPWAP HTTP based Portal Authentication
WiFi Offload Gateway Nodal test case the emulates UE performs Portal Authentication before data traffic starts.
In the WiFi offload Gateway Node test case, emulates Portal protocol server in AC to handle Portal Authentication Requests from the Portal Server Node. The Portal Authentication Node communicates with the RADIUS Server and Portal Server.
NOTE: The WiFi Offload Gateway Node performs Portal Authentication as follows:
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Following network elements are included in the Online and Offline Portal Authentication requests.
Online |
Online procedure performs user account certification, and informs the Portal Server authentication result. Portal Server then notifies WLAN users and displays the corresponding certification results. You may use static or dynamic login password. The Portal Server does not perform the final authentication (authentication method is defined in Radius Server. Support both PAP and CHAP authentication methods). |
Offline |
Support user initiated offline procedure, Force offline procedure and AC detected user offline and then notifies the Portal Server. User Initiated Offline Procedure:
Force Offline Procedure:
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UE/AP |
HTTP portal authentication request and response handling. |
AC |
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Portal Server |
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Measurements collected for this test case include:
Counters that record the number and types of messages sent and received
Average response times for the different types of messages received from an SUT
Errors encountered during the test
Wi-Fi UE Emulation
The multiple-Client/UE RF Wi-Fi functionality is built into the Wi-Fi Offload Nodal Test case. This functionality supports the emulation of large numbers of Wi-Fi clients with either an over-the-air or a cabled interface toward an Access Point (AP) and Access Controller SUT. This functionality requires one RF Client-emulation Wi-Fi NIC (Network Interface Card).
Each radio on the PCIe card is a fully functional WiFi capable of 3x3 (or 4x4) MIMO. The Card takes the outputs/inputs of the radio signal through a set of 3 (or 4) external SMA connectors. These connections can be attached to antenna for over-the-air testing or directly to cables for cabled testing. The connectivity between the MIMO radios and the SMA connectors is shown below.
| Card Type | #of Transceivers | Supported UEs per Single Transceiver | Supported UEs for all Transceivers per Card |
| 802.11AC | 1 |
64 |
64* |
| 802.11N | 1 |
200 |
200** |
*UI will allow configuration up to 256 UEs,
**UI will allow configuration up to 800 UEs
Example 1
In the above Example 1 configuration of the 802.11 Interfaces and Settings Table the test case is using two transceivers – wlan0 and wlan1. One is configured for 802.11n at 5 GHZ and the other is configured for 802.11ac at 5 GHZ. wlan0 only has Antenna 1 active/ON, so any UEs using wlan0 will only transmit SISO (1x1). Wlan1 is configured for 802.11AC at 5 GHZ. It has all 3 antennas active so if supported by the AP will transmit 3x3 MIMO. Both wlan0 and wlan1 will share the same Antenna1 in this configuration. The configuration is shown below from a logical internal mapping configuration within the Card.
Example 2
In the above Example 2 configuration of the 802.11 Interfaces and Settings Table the test case is using 3 transceivers – wlan0, wlan1 and wlan2. The first two are configured for 802.11ac at 5 GHZ and the 3rd is configured for 802.11n at 5 GHZ. Each of the 3 transceivers is configured for on SISO (1x1) support. The antennas are selected in such a way to isolate each of the 3 SISO Transceivers onto 3 different output antennas. Had each transceiver row selected the SAME antenna as ON they would have shared the same antenna. The configuration from the Example 2 configuration is shown below from a logical internal mapping configuration within the Card.
Example 3
In the above Example 3 configuration of the 802.11 Interfaces and Settings Table the test case is using 4 transceivers – wlan0, wlan1, wlan2 and wlan3. The first two are configured for 802.11ac at 5 GHZ and second two are configured for 802.11n at 2.4 GHZ. Each of the 4 transceivers is configured for on 3x3 MIMO support. The configuration from the Example 3 configuration is shown below from a logical internal mapping configuration within the Card.
Wi-Fi AP Emulation
The basic AP emulation is built into the Wi-Fi Offload Nodal Test case. This functionality is mutually exclusive with RF UEs interface. This functionality will simulate a software AP. Each AP supports up to 200 clients. Enable by selecting RF AP Emulation on the Wifi Offload Gateway Nodal Test Case. The AP RF Interface becomes available for input.
MU-MIMO Wave 2
- MU-MIMO APs transmit to different users at same time / same channel
- Transmit Beamforming allows AP to shape transmissions toward clients
- Clients are grouped: AP communicates to each group in parallel
- MU-MIMO Must be tested Over-The-Air
- MU-MIMO Require clients to be in diverse locations
- MU-MIMO Groups clients together
- MU-MIMO Throughput benefits measured across multiple different locations/groups
Null data packet (NDP) sounding - Goal of sounding is to calculate the feedback matrix (Beamformee) and Steering Matrix (Beamformer)
- The beamformer begins the process by transmitting a Null Data Packet Announcement frame, which is used to gain control of the channel and identify beamformees. Beamformees will respond to the NDP Announcement, while all other stations will simply defer channel access until the sounding sequence is complete.
- The beamformer follows the NDP Announcement with a null data packet. The value of an NDP is that the receiver can analyze the OFDM training fields to calculate the channel response, and therefore the steering matrix. For multi-user transmissions, multiple NDPs may be transmitted.
- The beamformee analyzes the training fields in the received NDP and calculates a feedback matrix. The feedback matrix, referred to by the letter V in the 802.11ac specification, enables the beamformer to calculate the steering matrix.
- The beamformer receives the feedback matrix and calculates the steering matrix to direct transmissions toward the beamformee.
Multi-User MIMO Transmission
Once the multi-user channel sounding is complete, an AP can proceed to send a multi-user transmission. Each beamformee in a multi-user transmission is called, a user. 802.11ac supports sending up to four multi-user MIMO transmissions at one time, and the 802.11ac MAC protocol includes ways to negotiate the capabilities of each of the simultaneous transmissions. Each multi-user MIMO transmission may have a different number of spatial streams and may have its own modulation speed and coding.
MU-MIMO transmissions are limited to four clients.
The complexity of multi-user MIMO transmission is illustrated in this Figure. Just as with single-user MIMO, there are potentially multiple paths between each of the AP’s antenna elements and the each of the users’ antenna elements. However, there is an additional complexity to multi-user MIMO in that the number of potential paths that need to be represented in the steering matrix includes every path between each of the AP’s antenna elements and every user antenna element. Each user transmission must be separately modulated.
Test Options
When your test activity measures processing capability, you can expand the scope of the test:
Add Data Traffic to the test to more closely simulate a live network using various wireless applications and protocols.
Measurements
Measurements collected for the basic test case are reported on the following tabs:
Additional measurements may be available depending on the test activity and options executed with the test case.