1. Best Practices for Zebra Enterprise Wi-Fi 7 Android Devices in HPE Aruba WLAN Infrastructure
  2. Wi-Fi 7 Devices Capabilities and Features
  3. Multi-Link Operation
  • Best Practices for Zebra Enterprise Wi-Fi 7 Android Devices in HPE Aruba WLAN Infrastructure
Multi-Link Operation

Multi-Link Operation

Multi-Link Operation (MLO) allows Wi-Fi 7 devices to simultaneously connect and transmit data across multiple frequency bands or channels, such as the 2.4 GHz, 5 GHz, and 6 GHz bands. By leveraging multiple links concurrently, MLO introduces a new paradigm of multi-band communication that enhances throughput, reduces latency, and ensures a more resilient connection in various networking environments.
Key benefits of MLO include:
  • Increased throughput
  • Reduced latency
  • Enhanced reliability
  • Optimized spectrum utilization
The table below explains the different ways multi-link devices can operate. It compares them based on their radio setup and whether they can send and receive data simultaneously. This will affect their speed and reliability.
Operating Modes
Transmit/Receive Capability
Radio
Description and Purpose
Relative Performance
NSTR (non-simultaneous)
Multi-Link Single-Radio (MLSR)
A single radio switching between different links (for example, 5 GHz and 6 GHz). The radio cannot transmit and receive simultaneously. This mode is used for load balancing and reducing latency compared to non-MLO, but does not aggregate speed and is sub-par to other MLO modes.
High
Enhanced MLSR (eMLSR)
While MLSR can listen to only one link at a time, the enhancement of eMLSR provides the ability to listen to multiple in parallel. Hence, eMLSR yields faster overall switching between links if one of them degrades in quality.
Multi-Link Multi-Radio (MLMR)
Multiple radios are synchronized to either transmit or receive at any given moment. This allows for link aggregation to achieve higher throughput by combining the bandwidth of multiple links for transmission or reception.
Higher
Enhanced MLMR (eMLMR)
In this NSTR mode, the eMLMR enhancement also enables dynamic link reconfiguration. This finer control of NSTR operations typically yields tangible improvements in throughput for traffic in a congested environment.
STR (simultaneous)
Multi-Link Multi-Radio (MLMR)
Multiple radios operate independently, allowing the device to transmit on one link while simultaneously receiving data on another. This is the highest-performing mode, offering the preferred throughput, lowest latency, and preferred reliability by enabling full-duplex communication across bands.
Highest
Enhanced MLMR (eMLMR)
In STR of Multi-Radio, the output performance and benefits can be achieved using either MLMR or eMLMR. The theoretical difference between them is eMLMR's ability to dynamically reconfigure links. However, given the STR nature, this enhancement may inherently introduce complexity and overhead, largely diminishing the need for it even in a congested environment and, in some cases, even degrading performance compared to the STR-MLMR.
Zebra Wi-Fi 7 devices are listed in the Table 1 Supported Wi-Fi 7 Devices support STR-MLMR, as shown in the third row in the Table 2 Operating Modes. When a Wi-Fi 7 network is configured in any Multi Link dual or tri-band possible configuration, in which, in all configuration cases, the APs are in STR-MLMR mode, the Zebra device’s MLO automatically interoperates in STR-MLMR.
The Zebra device STR-MLMR capability further ensures that the following very critical points are accomplished, beyond standard STR-MLMR operations and beyond the generic performance expectation mentioned in the above table:
  • The Zebra device constantly listens across multiple links to evaluate their quality. For each packet, it selects the best link for transmission. This dynamic selection process replaces complex link reconfiguration methods, such as STR-eMLMR. By dynamically selecting the best link, the device efficiently improves throughput and reduces latency in congested environments.
  • At the interoperability level between Wi-Fi 7 APs and Wi-Fi 7 devices, Zebra ensures that AP’s implementation of STR-MLMR and the device’s STR-MLMR fully interoperates and is further stabilized in collaboration with Enterprise WLAN network vendors. Most Wi-Fi 7 APs address the above-mentioned considerations to avoid the complexities of STR-eMLMR; thereby, this interoperability stabilization goes a long way.
  • Zebra's STR-MLMR support does not require any change in the device’s battery preservation or charging practices.
Singe and Multi Link Comparison
The Zebra’s MLO is supported when the WLAN network is set with either dual-band or tri-band MLO, in the following configuration combinations:
  • 2.4 GHz + 5 GHz
  • 2.4 GHz + 6 GHz
  • 5 GHz + 5 GHz
  • 5 GHz + 6 GHz
  • 2.4 GHz + 5 GHz + 6 GHz1
  • 5 GHz + 5 GHz + 6 GHz2
When operating in MLO, the maximum bandwidth supported for each link is as follows:
  • 2.4 GHz can support 20 MHz
  • 5 GHz can support up to 160 MHz
  • 6 GHz can support up to 160 MHz
The following charts compare the performance between Wi-Fi 6E (Single Link) and Wi-Fi 7 (Multi-Link) at 80 MHz and 160 MHz.
Comparison between Wi-Fi 6 and Wi-Fi 7 for 80 MHz
Comparison between Wi-Fi 6 and Wi-Fi 7 for 160 MHz
1 Up to two links can be active at any point in time.
2 Up to two links can be active at any point in time.