Furthermore, the higher the power allocation granularity, the more signaling overhead and thus performance degradation. The users in each group are served in the same orthogonal resource block following the NOMA principle, and different groups are allocated to different orthogonal resource blocks. Assuming a pair of users, one strong user (User 1) and one weak user (User 2) where User 1 has better channel conditions than User 2 (h_1>h_2), then the power allocated to User 1 will be less than the power allocated to User 2 (p_1 < p_2). A max-C/I scheduler would assign all the uplink resources to the UE with the best uplink channel conditions. Figure 1: Power-domain NOMA process within in a dominant and a weak of users. At the same time, based on the outcome of the RAN feasibility studies, 3GPP began to develop 5G specifications in two phases. From that point onward, there will be additional packet-routing delays which are beyond operator’s control. 3GPP has been studying the possibility of reducing the LTE TTI of 1 ms and to further identify additional latency reductions at layers 2 and 3 of the LTE protocol stack. Detailed timeline and process of 5G development in 3GPP (3GPP Work Plan, http://www.3gpp.org/specifications/work-plan). With greedy filling, the terminal with the best radio conditions is assigned as high a data rate as possible. In power-domain NOMA, x1 and x2 are superposed as x=P1x1+P2x2; thus the received signal at the ith UE can be written as yi=hix+wi, in which hi is the complex-valued channel coefficient between the ith UE and the base station, and wi denotes a zero-mean AWGN plus inter-cell interference. The ability to combine unlicensed spectrum with licensed spectrum is a highly attractive opportunity for network operators. For the time being, the evolution of mobile broadband will remain the most viable path because the demand for such services is proven to be strong and profitable for the operators and device/equipment vendors. This can be expressed as the maximum tolerable interference level at the base station, which is a shared resource. Product Highlights EnGenius Cloud Managed ECW230 Wi-Fi 6 (802.11ax) 4x4 Managed Indoor Wireless Access Point features 802.11ax technology, such as OFDMA, MU-MIMO, and spatial reuse, to expand the capabilities of Wi-Fi. Power control of uplink NOMA is different from that of downlink in two aspects. The base station scheduler in power-domain NOMA searches and pairs multiple users for simultaneous transmission at each subband. Strategies between greedy filling and max-C/I can also be envisioned as, for example, different proportional-fair strategies. This strategy maximizes the air interface utilization but is achieved at the cost of potentially large differences in data rates between users. What is NOMA or Non-Orthogonal Multiple Access? non-orthogonal multiple access (NOMA) is investigated for aerial base station (BS). For example, 5G might be dependent on low-band LTE for coverage and control channel signaling where such spectrum is not directly available for 5G. It can be seen that power allocation for each UE greatly affects the user throughput and thereby the modulation and coding scheme used for data transmission of each UE. Thus, for efficient packet-data access, a TDMA component should always be part of the uplink multiple-access scheme. In the downlink, the superposed signal received at a UE experiences the same channel, that is, the signals of different UEs have the same channel gain at each UE receiver. 3GPP Rel-15 is associated with the first phase of 5G specifications that define basic features of 5G systems. The same basic scheduling principles as for the downlink can be used. The Non-Orthogonal Multiple Access (NOMA) consist of serving multiple users on a unique resource block (space/ time/ frequency/ code), and with different power levels. For the uplink, due to different channels experienced by signals transmitted via different UEs, the received signal powers of different UEs already have differences in the power domain. A preliminary study on 5G candidate technologies was conducted as part of 3GPP Rel-14 that was concluded in March 2017 [15]. In this chapter, we explore the concept of non-orthogonal multiple access (NOMA) scheme for the future radio access for 5G. In [172], hybrid NOMA was proposed for a relay-assisted network. It is one of the many technologies that promise greater capacity gain and spectral efficiency than the present state of the art, and as such, is a candidate technology for 5G cellular net- NOMA is a new technology proposed to ensure that multiple users are accommodated within the same spectrums, thus improving spectral usage efficiency. The computational complexity is higher because each user has to decode not only its own signal, but the signal of other users too (to apply SIC), leading to a longer delay. Fundamentally, the uplink power resource is distributed among the users, while in the downlink the power resource is centralized within the base station. Furthermore, authors in (Martin-Vega et al., 2017) studied a NOMA-enabled CRAN framework by considering the NOMA based scheduling of two users in the same resources in combination with coordinated beamforming to enhance the performance of cell-edge users. In fact, this non-orthogonal concept is a generalized framework of recently proposed different multiple access schemes for 5G and beyond wireless networks such as power-domain NOMA, sparse code multiple access, lattice partition multiple access, multi-user shared access, and pattern division multiple access. This can be expressed as the maximum tolerable interference level at the base station is a shared resource. As discussed in Chapter 2, a wide bandwidth is needed to support high data rates in a power-efficient way. The analytical expressions for outage probability have been derived for both the nearby and cell-edge users. The above discussion on non-orthogonal multiple access was simplified in the sense that no bounds on the UEs’ transmission power were assumed. A max-C/I scheduler would assign all the uplink resources to the terminal with the best uplink channel conditions. In case of a non-orthogonal multiple-access scheme, greedy filling is one possible scheduling strategy [7]. Nonorthogonal multiple access (NOMA) principle emerges as a solution to improve the spectral efficiency while allowing some degree of multiple access interference at receivers. This book discusses non-orthogonal multiple access (NOMA) and the various issues in NOMA networks, including capability, sustainability, and security. Also known as AX Wi-Fi or 802.11ax Wi-Fi, Wi-Fi 6 builds and improves on the current 802.11ac Wi-Fi standard. This allows simultaneous low-data-rate transmission from several users. The interference constraints [155] can be represented as. The 3GPP services and requirements working group has contributed to the study phase for 5G service requirements, known as SMARTER [21]. 18. In the extreme case, a user at the cell border with poor channel conditions may not be allowed to transmit at all. However, scheduling is equally applicable to uplink transmissions and to a large extent the same principles can be considered, although there are some differences between the two. Although previous studies have investigated the typical relationship between the SH and winter … The key technologies identified for NOMA-enabled H-CRANs include massive MIMO, cognitive radio, mmWave communications, wireless charging, cooperative transmission, and device-to-device (D2D) communications. Describe what Non-orthogonal multiple access (NOMA) is Describe different modulation techniques in mobile communication Describe power-level modulation Describe key metrics for evaluation of modulation techniques Describe advantages and disadvantages of NOMA Despite the availability of related hybrid-NOMA studies, it is currently unclear if such techniques are suitable for multi-UAV HBD-UCSs. In addition, there is a different approach to transmit power control in the uplink. He is currently an Early Stage Researcher under the ITN project SPOTLIGHT at MTN Cyprus and studying towards a Ph.D in the Department of Electrical and Computer Engineering at the University of Cyprus. If UEs are not power limited, then it is preferable to schedule users only in the time domain in the WCDMA uplink, because TDM scheduling maintains orthogonality between users. An optimization problem to maximize the energy efficiency was formulated under the constraints of transmit powers at the central unit and RRHs as well as devices’ QoS. It is then possible to … If any errors occur during the SIC process, then the error probability of successive decoding will be increased. Depending on the instantaneous QoS, power-domain NOMA is employed if the instantaneous QoS enables a greater ergodic capacity to be achieved. Thus, with non-orthogonal multiple access, scheduling a UE when the channel conditions are favorable may not directly translate into a higher data rate as the interference generated to other simultaneously transmitting UEs in the cell must be taken into account. Unlike the downlink, where pure TDMA often can be used, uplink scheduling typically may have to rely on sharing in the code domain in addition to the time domain as a single UE may not have sufficient power for efficiently utilizing the link capacity. Hence, the resource assigned for the weak user is also used by the strong user, and the interference can be mitigated through SIC processes at the receiver.