Option 8 (PHY-RF split): This option allows to separate the RF and the PHY layer. Option 5 assumes the following distribution: Therefore, by splitting the MAC layer into 2 entities (e.g. In the DL, iFFT, CP addition, resource mapping and precoding functions reside in the DU, the rest of PHY functions reside in the CU. CA, eICIC, CoMP etc. Functional architecture is described as “an architectural model that identifies system function and their interactions. A functional software architecture (FSA) is an architectural model that identifies enterprise functions, interactions and corresponding IT needs. Generally, more than one architecture can satisfy the requirements, Berton Manning for the Department of Defense (DoD). In the downlink, iFFT and CP addition reside in the DU and the rest of the PHY resides in the CU. Option 6 (MAC-PHY split): The MAC and upper layers are in the central unit (CU). Conceptual Architecture vs Logical Architecture : Conceptual Architecture: Logical Architecture: Definition: Architecture that includes as little detail as possible in order to plan or communicate basic structures. The interface between the CU and DUs carries data, configuration, and scheduling-related information (e.g. In the DL, iFFT and CP addition functions reside in the DU, the rest of PHY functions reside in the CU. functional, behavioral, and temporal) Transform the defined set of technical requirements into a set of logical Fs-C and Fs-U provide control plane and user plane connectivity over Fs interface. The inter-cell interference coordination in the High-MAC sublayer will be in charge of interference coordination methods such as JP/CS CoMP. From an abstraction level viewpoint, it represents a middle ground, sitting between the Conceptual and Physical architectures. is that functional is (computing) an object encapsulating a function pointer (or equivalent) while logical is (computing) non-physical or conceptual yet underpinned by something physical or actual. The idea of decomposing a system’s speci cation along several ‘levels of abstrac-tion’ constitutes good practice in the eld of software engineering. This option requires some kind of compression technique to reduce transport bandwidth requirements between the DU and CU. Functional Decomposition • Functional decomposition is a cornerstone of systems engineering processes. C-plane since some new procedures may be needed. Logical architecture describes how a solution works in terms of function and logical information. This technique turned out Logical Decomposition Purpose The Logical Decomposition Process is used to: Improve understanding of the defined technical requirements and the relationships among the requirements (e.g. The functional view de nes the functions that a user can invoke at the boundary of the system. MAC, physical layer, and RF are in the distributed unit. What is Inter Symbol Interference (ISI) in LTE, How Cyclic Prefix (CP) helps eliminating this problem ? This allows efficient support of functions such as CoMP, MIMO, load balancing, mobility. Option 7-3 (Only for DL): Only the encoder resides in the CU, and the rest of PHY functions reside in the DU. It takes high-level centralized scheduling decision. In addition, this option can be achieved by separating the RRC and PDCP for the CP stack and the PDCP for the UP stack into different central entities. In High-MAC sublayer the centralized scheduling in the High-MAC sublayer will be in charge of the control of multiple Low-MAC sublayers. For example, a diagram that illustrates the relationship between software components. RLC, MAC, physical layer and RF are in the distributed unit. In this architecture, Central Unit (CU) and Distribution Unit (DU) can be defined as follows. It includes a functional architecture, a behavioral architecture, and a temporal architecture [2]. low latency, high throughput), Support of specific user density and load demand per given geographical area (which may influence the level of RAN coordination), Availability transport networks with different performance levels, from ideal to non-ideal, Application type e.g. Real-time or Non- Real Time. Considering above there are three sub-variant available for this option described as below. Low RLC may be composed of segmentation functions; High RLC may be composed of ARQ and other RLC functions; Low RLC may be composed of transmitting TM RLC entity, transmitting UM RLC entity, a transmitting side of AM and the routing function of a receiving side of AM, which are related to downlink transmission. In this architecture, Central Unit (CU) and Distribution Unit (DU) can be defined as follows. A central unit (CU) may also be known as BBU/REC/RCC/C-RAN/V-RAN. To further the confusion, the word "Architecture" tends to be associated with either “Requirements” or “Logical” whereas "Design" tends to be associated with “Physical.” This probably stems from the fact that we, the I/S community, are starting at Row 3 and in an absolute, Enterprise sense, don’t … Generally, more than one architecture can satisfy the requirements. Flexible HW implementations allows scalable cost-effective solutions, A split architecture (between central and distributed units) allows for coordination for performance features, load management, real-time performance optimization, and enables NFV/SDN, Configurable functional splits enables adaptation to various use cases, such as variable latency on transport, Support of specific QoS per offered services (e.g. The logical view de nes the internal implementation of the system as a hierarchy of components. Unlike these, however, logical architecture is quite broad in scope. In a functional architecture, the basic unit is also a function, but a much larger business-oriented one that I like to call a workflow. High RLC may be composed of receiving TM RLC entity, receiving UM RLC entity and a receiving side of AM except for the routing function and reception of RLC status reports, which are related to uplink transmission. It includes a functional architecture, a behavioral architecture, and a temporal architecture. The primary difference between logical and physical architecture documentation is that, while logical architecture's concerns end with identifying functional elements of the system, physical architecture takes an additional step, specifying actual devices that those functional elements execute on. What exactly is the difference between the logical and the physical design?There are a plethora of logical and physical architecture diagrams throughout the IT world, so many in fact that we expect to find them in our literature. Option 2-2: In this split option, RRC, PDCP are in the central unit. Option 7-2 In this option the UL, FFT, CP removal, resource de-mapping and possibly pre-filtering functions reside in the DU, the rest of PHY functions reside in the CU. logical architecture. ISO 5 defines logical architecture as: The logical architecture of a system is composed of a set of related technical concepts and principles that support the logical operation of the system. Logical architecture is a structural design that gives as much detail as possible without constraining the architecture to a particular technology or environment. Really, the only limitations are the performance and capabilities of the physical device. For the initial phase, 3GPP has taken LTE protocol stack as a basis for the discussion, until RAN2 defines and freezes the protocol stack for New Radio (NR).