An Introduction to OFDMA Technology
OFDMA (Orthogonal Frequency-Division Multiple Access) is a wireless network technology that allows multiple devices to access a WiFi network efficiently without interfering with each other. It builds upon the basic OFDM modulation scheme used in most modern WiFi networks.
In OFDM, the available bandwidth is divided into several smaller sub-channels that transmit data in parallel. This makes it resilient against interference and signal fading.
OFDMA takes this concept further by assigning subsets of these sub-channels to individual devices dynamically rather than making the entire bandwidth shareable by everyone. As such, OFDMA allows multiple devices to transmit WiFi signals simultaneously without collisions.
How Does OFDMA Work?
OFDMA WiFi works on the principle of orthogonality. This means that the carrier signals of sub-channels are totally independent of each other when viewed over a particular time frame.
- The WiFi router or access point divides the available bandwidth into smaller sub-carriers spaced orthogonally.
- These sub-carriers are then grouped into resource units.
- When a device needs to transmit data, the router allocates one or more resource units to it based on demand.
- As these resource units do not overlap, multiple devices can use the WiFi spectrum concurrently without interference.
Diagram showing subcarrier allocation in OFDMA WiFi
The router tracks data transmission requirements from each connected device and keeps allocating resource units accordingly in each time interval. This scheduling of spectrum access is what ensures efficient sharing of the available bandwidth.
Advantages of OFDMA WiFi
OFDMA brings several key improvements over older WiFi versions:
1. Higher Network Capacity
By allowing multiple devices to transmit simultaneously, the overall traffic capacity of the WiFi network goes up substantially. More devices can be connected without congestion.
For example, the maximum speed for a client device under 802.11ac WiFi is 866-867 Mbps depending on bandwidth. The same router using OFDMA can deliver data rates in excess of 1 Gbps through efficient spectrum sharing.
2. Lower Latency
The scheduling algorithms used under OFDMA ensure that devices get continuous data access without having to contend for it. This brings down latency metrics significantly while delivering data to multiple devices parallelly.
Games and multimedia applications perform far better as a result of reduced lag and latency. Around 2-5 ms ping times can be achieved through OFDMA WiFi.
3. Better Co-Existence
OFDMA has mechanics in place so that devices based on older WiFi standards can work nicely alongside newer OFDMA capable devices on the same network without affecting each other’s performance. This ensures good compatibility and transition into this newer technology.
4. Extended Battery Life
Battery-operated devices such as smartphones, tablets and IoT devices benefit the most from OFDMA. The scheduling algorithm ensures they only power up their antennas when data access is scheduled.
At other times, these devices can switch to sleep mode. This extends battery runtime by 30-60% for such devices.
5. Supports High Density Deployment
Public places like malls, auditoriums and railway stations which see extremely high footfall can now provide good quality WiFi to users through OFDMA. It allows efficient serving of many concurrent users from the same wireless access point without deterioration in experience.
When Was OFDMA Introduced?
OFDM modulation started being adopted in WiFi networks in late 1990s itself beginning with 802.11a and g standards, due to its resilience to interference.
However, multi-user access through OFDMA only became part of the WiFi standard in 2017 with the introduction of:
- 802.11ax – Next gen WiFi 6/6E devices
- 802.11ac – Latest WiFi 5 devices (via firmware updates)
These standards introduced OFDMA support along with several other enhancements using advanced signal processing and beamforming techniques.
The latest WiFi 7 devices (802.11be) launched in 2023 also build upon the OFDMA framework with wider bandwidth channel support going up to 320 MHz.
Is My Device Compatible With OFDMA?
To benefit from OFDMA WiFi networks fully, you need hardware which supports 802.11ax or 802.11ac standards. Software updates may bring partial OFDMA support to some older devices.
WiFi 6 Devices (802.11ax)
Any WiFi router, laptop, smartphone or tablet launched from 2019 onwards with WiFi 6 compatibility is likely to work seamlessly on OFDMA networks without requiring any firmware updates. These devices were designed keeping this technology in mind.
For example, Samsung Galaxy S10 series launched in 2019 brought in native built-in OFDMA support.
WiFi 5 Devices (802.11ac wave 2)
Top-end WiFi 5 routers and laptops launched from 2016 onwards support OFDMA through firmware updates to existing hardware. For smartphones, OFDMA support came later from 2018 onwards.
Contact your device manufacturer to check for OFDMA compatibility updates if your model is 802.11ac wave 2 compliant.
Older WiFi 4/5 Devices (802.11n/ac wave 1)
These older devices (before 2016) can still connect to OFDMA networks in a limited manner. The scheduling algorithm allocates some non-OFDMA channels so they receive timely data access without collisions.
But their performance is not optimized for multi-user transmissions. You’ll get much better experience by upgrading to latest hardware.
Setting Up an OFDMA-Capable WiFi Network
To deploy OFDMA practically at home or for your business, here is what you need:
- OFDMA Supported Router – A latest WiFi 6/6E or WiFi 7 router which encodes OFDMA compatibility such as Netgear Nighthawk AXE11000.
- OFDMA Clients – Laptops, smartphones and tablets purchased in recent years with WiFi 6/6E support will directly work with OFDMA.
- Up-to-Date Firmware – Keep router and client device firmware updated to leverage the latest wireless capabilities optimally.
- 5 GHz Band Preferred – Use 5 GHz instead of 2.4 GHz band on devices for OFDMA access and better performance.
- Wider Channels – OFDMA works best with 80 MHz and wider channel bandwidths subject to regulatory approval.
- MU-MIMO Support – Having multiple-input multiple-output (MU-MIMO) support boosts OFDMA performance for multiple clients.
Industry Adoption of OFDMA Technology
The enhanced spectral efficiency and high data capacity delivered by OFDMA has seen rapid adoption across many wireless networking domains:
- All WiFi 6 and 6E devices today come with OFDMA support built-in as part of the 802.11ax standard released in 2019.
- Many cellular network providers have deployed it in 4G networks globally through LTE-Advanced Pro standard by 3GPP.
- WiFi 7 standard (802.11be) launched in 2023 requires mandatory OFDMA support at 6 GHz and higher bands.
- The upcoming 5G-Advanced releases will leverage OFDMA at mmWave spectrum for efficient multi-gigabit delivery.
- IEEE 802.11ad standard uses OFDMA at 60 GHz unlicensed spectrum to deliver ultra-high-speed short-range connectivity.
- WFA EasyMeshTM – An interoperable standard by WiFi Alliance uses OFDMA links between mesh network nodes.
Clearly, OFDMA has become pivotal for wireless technologies to keep pace with today’s dense deployments and bandwidth hungry applications.
- OFDMA WiFi allows the spectrum to be shared dynamically between devices leading to efficient multi-user transmissions in parallel. This brings huge boosts in network capacity, speed and range without requiring more routers.
- Support for OFDMA requires WiFi 6, 6E or WiFi 7 hardware on both router and client devices. Partial compatibility exists for some older 802.11ac Wave 2 devices as well through firmware updates.
- With concepts like scheduling algorithms, MU-MIMO and wider channels complementing it, OFDMA delivers a gigantic leap over older WiFi versions a through better user experience.
- Given its benefits for 5G, WiFi 7 and unlicensed 60 Ghz connectivity, OFDMA stands out as one of the most crucial wireless technologies for the next decade with growing industry adoption.
With the vast number of devices using WiFi growing each year, traditional WiFi standards are no longer able to cope up and provide reliable performance for everyone. OFDMA changes this status quo profoundly through dynamic channel sharing allowing extremely high concurrency. With devices across smartphones, PCs, tablets, IoT appliances supporting WiFi 6/6E now in billions, OFDMA is all set to become ubiquitous soon across homes and enterprises.
Frequently Asked Questions
- What is OFDMA in simple terms?
OFDMA or Orthogonal Frequency Division Multiple Access allows multiple devices to transmit data concurrently on a WiFi network without interference. This increases the total bandwidth capacity and speed available for users.
- Does OFDMA increase WiFi range?
Indirectly yes. As the same WiFi router can now support 3-4x more client devices efficiently, users experience better signals even farther from it due to less crowding.
- Is OFDMA better than MU-MIMO?
OFDMA and MU-MIMO complement each other. MU-MIMO allows multiple transmit paths to same client while OFDMA allows multiple clients to transmit simultaneously. Having both gives best WiFi performance.
- Why has OFDMA not been used before in WiFi?
The complex digital signal processing required for dynamic subcarrier allocation was not feasible in older WiFi router hardware. Advances in silicon only recently enabled cost-effective OFDMA support.
- Can all my devices use OFDMA?
Probably not. OFDMA needs WiFi 6 or newer hardware released 2019 onwards on both router and client side. Some older 802.11ac Wave 2 devices may support it through firmware update.
- Will OFDMA give speed boost to older devices?
Partial benefit. Scheduling algorithms will allocate airtime for non-OFDMA devices too. But their performance is still limited by older WiFi standards in use.
- Is there any drawback of OFDMA WiFi?
It does lead to increased battery drainage on mobile devices as their WiFi needs to stay on for greater durations owing to scheduling algorithms. Frequent recharge may be required.
- Does OFDMA require special routers?
Yes, you need latest WiFi 6 or WiFi 6E router supporting 802.11ax standard. WiFi 7 routers will also have mandatory OFDMA support. Old 802.11ac wave 2 routers may work through firmware update.
- What is the difference between OFDM vs OFDMA?
OFDM allows efficient modulation scheme for a single transmission link using orthogonal subcarriers while OFDMA allows multiple access on top by scheduling spectrum subcarrier allocation between different concurrent transmitting links.
- Can all devices take advantage of OFDMA simultaneously?
In practical scenarios with mixed client devices, around 70-80% can use OFDMA at any time while scheduler allocates non-OFDMA channels for the remaining. So benefit is still substantial.
- Is OFDMA compatible with Bluetooth or Zigbee?
Yes, OFDMA transmission is quite resilient against interference from Bluetooth, Zigbee and other wireless technologies operating in nearby bands. Co-existence is not an issue.
- How is OFDMA different from MIMO?
MIMO refers to use of multiple spatial streams through multiple antennas while OFDMA refers to allowing multiple devices to transmit concurrently over same channel. MIMO helps each client get speed boost while OFDMA increases overall network capacity.
- Will a device get fullWIFI speed with OFDMA?
Depends whether device supports latest WiFi 6E or WiFi 7 standard. If not, maximum possible speed will be still limited by older WiFi5 standard even while using OFDMA channel scheduling.
- Does OFDMA require more power?
Yes, additional digital signal processing results in higher computation requirements on device CPU/GPU leading to somewhat increased power consumption.
- Can two routers provide a boost with OFDMA?
Yes, dividing entire spectrum into more number of orthogonal sub-carriers through two WiFi6/6E routers and then scheduling client access can enhance performance even further.
- What is the likely data speed I can expect from OFDMA WiFi?
With 80 MHz channels, around 100-150 Mbps real-life speeds are quite practical for smartphones. Laptops can get 500-800 Mbps based on model of adapter. Newer WiFi 7 can deliver multi-gigabit speeds.
- Is OFDMA used in 5G technology?
Yes, 5G NR networks already use OFDMA at sub-6Ghz bands. The upcoming 5G-Advanced release also plans to leverage OFDMA at mmWave frequencies for efficient multi-Gbps delivery.
- Does weather impact OFDMA performance?
Heavy rain or snow can potentially hamper signal transmission if devices are too far from router. But OFDMA resilience to multipath interference means performance degradation will be modest for most users.
- Can too many devices slow down OFDMA WiFi?
Theoretically no, since the scheduling algorithms keep allocating spectrum continuously between devices. But if too many older WiFi 5 clients are connected, their individual performance may reduce a bit.
- Is OFDMA used in WiFi 7 standard?
Yes, WiFi 7 or 802.11be makes OFDMA support mandatory at 6 GHz and higher frequency channels. This build further upon the OFDMA framework already present in WiFi 6 standard.