The AT&T-inspired XRAN open framework has gained support from antenna maker CommScope, which is tapping into the trend for open source hardware in the evolving 5G landscape.
The firm has announced a 5G radio/antenna solution based on the XRAN interface specifications, which allow RAN hardware from multiple vendors to be mixed and matched, which will be particularly important in Cloud-RAN, enabling basebands to be connected to radio/antennas from other suppliers.
The CommScope radio/antenna takes instructions from a virtualized baseband via the open interface and integrates a beamforming active antenna array operating in the 28 GHz millimeter wave band.
Initially, it is targeted at fixed wireless access (FWA) – the US operators are trialling fixed 5G networks in this band – and CommScope says MNOs can use COTS (commercial off-the-shelf) servers to trial virtualized network functions for FWA applications.
The solution includes a base station antenna with 120-degree beamsteering of four independent MIMO ports, using a CommScope patented 256-element antenna array; plus an integrated remote radio unit housed in a compact enclosure of less than 10 litres in volume, passively cooled.
“Our integrated antenna will enable the full capabilities of 5G millimeter wave spectrum bands while offering maximum flexibility in an evolving air interface environment,” said Farid Firouzbakht, SVP of RF products. “As a contributing member to the XRAN organisation, we endorse the benefits of an open baseband interface for enabling more innovation in the wireless marketplace.”
Members of XRAN include AT&T, Deutsche Telekom, Telstra, Verizon and SK Telecom, plus Nokia, Intel, Texas Instruments, Aricent, Radisys, Mavenir and Cisco.
At the turn of the year, the open source XRAN.io group released its first specs, based on work to decouple the RAN control plane from the user plane. It has been working first on three areas which will help to transform the RAN:
• standardized northbound and southbound interfaces to make it easier to deploy services and achieve multivendor networks, in a decoupled, software-defined environment.
• implementation of RAN software and network functions on off-the-shelf hardware,including the modular xRAN LTE eNode B base station software.
• and the flexibility for operators to run software functions at the macro cell site or at the edge of the network, depending on availability of fronthaul links.
Although the initiative started in AT&T, which has contributed technology, there are inputs from other members, which include virtualized packet core supplier Mavenir (also a leading light in the open source CORD group). The group is trying to avoid third party intellectual property in its specs, presumably to maximize the cost and innovation benefits of open source while protecting adopters from exposure to patent fees down the road.
Mavenir says it has the specs already running and in trials with four large carriers. According to Mavenir’s John Baker, the next piece of work will be the operation and management (OAM) interface. Baker says xRAN is working with five or six RRH suppliers and he expects commercial hardware to be available in the first half of 2018, adding to the challenges to the traditional proprietary, end-to-end model for the RAN, which has been dominated by a shrinking group of large vendors.