/ˌoʊ.fɪdˈeɪ.mə/
noun — "a technique that divides bandwidth into multiple subcarriers for simultaneous transmission."
OFDMA, short for Orthogonal Frequency-Division Multiple Access, is a multi-user version of OFDM that allows multiple devices to transmit and receive data simultaneously over a shared channel. By splitting the available frequency spectrum into orthogonal subcarriers and assigning subsets of these subcarriers to different users, OFDMA efficiently utilizes bandwidth and reduces interference in wireless communications.
Technically, each user in OFDMA is allocated a group of subcarriers for a specific time slot, allowing parallel transmission without collisions. This is achieved by maintaining orthogonality between subcarriers, which ensures that signals from different users do not interfere despite overlapping in frequency. OFDMA is widely used in modern cellular networks such as LTE (LTE) and 5G-NR (5G-NR), as well as in Wi-Fi 6 (802.11ax), providing high spectral efficiency and low latency for multiple simultaneous users.
Key characteristics of OFDMA include:
- Multi-user access: multiple devices share the same frequency band simultaneously.
- Subcarrier allocation: frequency resources are divided into orthogonal subcarriers for each user.
- Spectral efficiency: maximizes utilization of available bandwidth.
- Low interference: orthogonal subcarriers prevent cross-talk between users.
- Scalability: supports a large number of users and varying data rates efficiently.
In practical workflows, OFDMA enables mobile networks to serve multiple users with diverse bandwidth needs efficiently. Network engineers allocate subcarriers dynamically based on demand, user location, and channel conditions, optimizing throughput and latency. In Wi-Fi environments, OFDMA allows simultaneous transmissions from multiple devices to reduce congestion in high-density areas.
Conceptually, OFDMA is like dividing a highway into lanes for multiple cars, letting each vehicle travel simultaneously without collisions, maximizing the road’s capacity.
Intuition anchor: OFDMA orchestrates multiple transmissions over the same spectrum, enabling efficient, high-speed communication for numerous users.