Two important standards for wireless communication are UMTS-LTE (Universal Mobile Telecommunication Standard, Long Term Evolution) advocated by 3GPP (Third Generation Partnership Project) and Wi-Fi (IEEE 802.11 series) advocated by IEEE (Institute of Electrical and Electronics Engineers).
UMTS-LTE supports communication by orthogonal frequency division multiple access (OFDMA), while current versions of the IEEE 802.11 standards (e.g. 802.11g, 802.11n, 802.11ac) operate based on carrier sense multiple access with collision avoidance (CSMA/CA).
In the current versions of the IEEE 802.11 standards, the channel access is typically distributed among the nodes (access point—AP, stations—STA) using the distributed coordination function (DCF), which means that all nodes contend for the channel when they have data to send.
In the next generation of Wi-Fi, denoted HEW (High Efficiency WLAN—Wireless Local Area Network) or 802.11ax, OFDMA is introduced to improve the performance in dense deployments. Since there is a huge number of legacy Wi-Fi devices on the market (e.g. basing their operation on any of the standard versions 802.11g, 802.11n, 802.11ac), it is desirable that the introduction of OFDMA be made to allow support also for legacy devices.
It should be noted that similar situations may occur in other scenarios than those of IEEE 802.11.
Therefore, there is a need for methods and arrangements that provide coexistence of OFDMA and CSMA/CA.