Software-Defined Wireless Networks (SDWN):

The SDWN was developed to allow the existing mobile networks to act as operator-definable networks for further mobile applications and new solutions [17] – [18]. Thus, SDWN presents the heterogeneous mobile wireless network efficiently to illustrate the 5G mobile network. It composed of several wireless mobile technologies such as (Wi-Fi, LTE, etc.) and various coverage layers such as (small and macro celllayers) over heterogeneous cellular edge networks along with the core network.

Consequently, the SDWN controller provides service providers with the benefits of easier deployment of new services, the reduced management cost of various technologies, efficient operation of multi-vendor infrastructures, increased accountability, service differentiation, continuous network operation, and transparent enhancement of network operation [20].

Wireless technology platforms:

This innovation has started in 1999 with an open-source telephone switch called Asterisk. Subsequently, several open-source projects have developed by several companies and research institutes, including both the hardware and software, compatible with today’s standard mobile phone. Software Radio Systems, Fraunhofer FOKUS, Range Networks, Sysmocom, OpenBTS, OpenLTE, and EURECOM are some of the most prominent companies and research institutes who have been developing open-source mobile communication software projects. The combination of open-source mobile communication software with the Software Defined Radio (SDR) provides the potential to achieve a better cellular system, about cost, time, and flexibility.

The SDR technology contains the pledge of a universal and fully programmable wireless communication system. Based on a universal hardware platform, SDR tries to implement various radio functions over software instead of the traditional radio design ideas that are depending on fixed hardware for a particular purpose. Consequently, a combination of programmable radio frequency (RF) frontend with a baseband processing platform can be constructed to form an SDR Platform.

The Universal Software Radio Peripheral (USRP) provided by Ettus research is the most famous RF frontend (see Figure 12) [21]. Moreover, to establish a baseband processing platform, General Purpose Processor (GPP) is selected by most SDR designers to execute functions like signal generation, coding/decoding, modulation/demodulation, etc. The combination of USRP RF frontend and GNU Radio [22] an open-source baseband processing Platform GPP based, is the leading SDR platform for research communities to interact with the next generation of telecommunication architecture. Furthermore, both the research community and the commercial sector are highly interested in this Platform. Thus, SDR is now recognized as the third revolution following the fixed-to-move, analog-to-digital in the communication [23].

Hence, in this section, we investigate the most popular mobile communication alternatives (namely, Amarisoft, OAI, and srsLTE) that provide a full LTE protocol stack.

OpenAirInterface Emulation Platform: 

OpenAirInterface (OAI) is a powerful and flexible wireless technology platform based on the 4G ecosystem that contains the entire LTE protocol stack released under the AGPLv3 license, including standard-compliant implementations of the 3GPP LTE access stratum for both evolved node B (eNB) and UE and a subset of the 3GPP LTE Evolved Packet Core (EPC) protocols. OAI can be adopted as an emulation and performance evolution platform for LTE/LTE-A systems [24].

Moreover, the current development is written in C targeting both real-time and non-real-time operations and run on standard Linux-based computing equipment ranging from a simple PC to a sophisticated PC cluster or even a GPU workstation, which is distributed deployment on a local network to transmit information via the IP address.

Two unique features of the OAI platform are [25]:

1) An open-source software implementation of the 4th generation (4G) mobile cellular system that is fully compliant with the 3GPP LTE standards witch can interoperate with commercial terminals and can be used for real-time indoor/outdoor experimentation and demonstration.

2) Built-in emulation capability that can be used within the same real execution environment to transition between real experimentation and repeatable, scalable emulation. Correctly, two physical layers (PHY) emulation modes are supported, which differ in the level of detail at which PHY is realized.

srsLTE Platforms:

srsLTE is software for SDR applications that provides a full LTE protocol stack for both srsENB (as LTE eNB) and srsUE (as LTE UE). Thus, this software has a lightweight LTE core network implementation. srsLTE was released under the AGPLv3 license and used software from OpenLTE project for some security functions and NAS parsing. Additionally, this software is available under both Open source and commercial licenses. Also, the SRS software suite includes some custom products such as AirScope and the over-the-air LTE analysis toolbox.

The current development of srsLTE written in a C/C++ language targeting both real-time and non-real-time operations and running on standard Linux-based computing equipment ranging from a simple PC to a sophisticated cluster or even a GPU workstation. srsLTE platform supports a distributed deployment on an IP local network.

For real-world experimentation and validation, srsLTE includes support for Sidekiq M.2 SDR from Epiq Solutions. The two platforms support NI/Ettus Universal Software Radio Peripheral(USRP) B2x0/ N210/X3x0, LimeSDR, and BladeRF.