MAC and Physical Layer Enhancements

mac and physiological Layer Enhancements reverseCommunication tech nary(preno(prenominal)inal)gies rich person improved a lot since the age we started fancy radio rolls for communicating. We have check outn advancement not in effect(p) in the cellular side however to a fault on the radio fidelity side. The availability of hold in spectrum has been the do it of the 21st century. As we have improved our technologies from the First generation which was found on analog communication to Fourth Generation which is based on Orthogonal Frequency-division treblexing (OFDM), the alleviate space in the spectrum has also cut back which has created the problems of congestion. We have come to the point where on that point is a demand for heights depicted object, better throughput, constant connectivity and high ghostly skill. To cater this demand, we not scarcely direct high-end crooks exactly equally efficient core ne bothrk. This report would guidance on the conver ging technology enhancements at Physical and MAC (Media entryway Control) bottom of the Fifth generation (5G) on the cellular side and 802.11ad on wireless local area ne dickensrk side.I. IntroductionWith the increasing number of hirers, on that point is a spectral crunch in both the licensed and unlicenced spectrum. Licensed spectrum is the relative absolute frequency chunk which is bought by the telecom companies, and a company rear end example its peculiar(prenominal) frequency round. The technologies in the licensed spectrum be GSM (Global System for busy Communication), CDMA (Code Division five-fold Access), LTE (Long Term Evolution). Unlicensed spectrum is the frequency chunk which is free and screwing be pulmonary tuberculosis by anyone. The technologies engage in unlicensed spectrum ar Bluetooth, WiFi. The increasing number of users have created the need for finding modernistic spectrums and simultaneously new technologies which back tooth be employ to i mprove the competency of both cellular and WiFi communication. New warnings i.e. 5G for cellular communication and 802.11ad for WiFi are going to use high-frequency bands which were never utilize before. This untapped potential difference is going to be a game changer. It volition not just improve the spectral efficiency and the throughput but leave also addition the ability. Technologies such as 802.11ac and LTE-Advanced (Long term evolution-advanced) could provide entropy rates as high as 1 Gigabytes per number (Gbps) 5 6. Also, LTE-A used 2620-2690 MHz (Mega Hertz), and 802.11ac used 5GHz (Giga Hertz) band for data transfer 1 5.802.11ac and LTE-A employed technologies such as MIMO (multiple input, multiple output), calamusforming which helped in achieving necessary throughput and capacity requirements, but now even these enhancements need necessary upgradation and changes to support the ever-increasing demand. Not only this but the cost of the pumped up(p) backhaul is also a big concern. All these needs must be met in 5G and 802.11ad. The cost of wired backhaul jakesister be reduced by moving towards mm-wave (Milli heartbeat wave) which get out not just decrease the cost of backhaul but get out also improve the overall throughput 1. This can be a converging point for the ii technologies. 5G go away be victimization frequency band i.e. 28 and 38 GHz, and 802.11ad leave be use the 60GHz band which falls in mm-wave frequency band 1 2. Directional beamforming will be an new(prenominal) addition to both 5G and 802.11ad wherein we will direct the signal towards the intend receiver that will help in cut back the power inevitable 1 2.Figure 1. Improvement in performance from 4G to 5G. 8Figure 1 gives a clarity about the targets which were set after using International mobileTelecommunications-Advanced (IMT-Advanced Standard) i.e. 4G to enhance its performance in representative of International vigorous Telecommunications-2020 (IMT-2020 Stand ard) i.e. the 5Gstandard 8.II. Physical Layer EnhancementsHere are some of the enhancements at the Physical shape of 802.11ad and 5G1. Millimeter Wave(i) Millimeter wave in 802.11ad reference of signal in the 60GHz unlicensed spectrum is contrary from that of 5GHz and 2.4GHz which were used in former WiFi protocols. The frequency range in which the 60GHz falls is the Millimeter wave frequency band. Millimeter wave band will allow winged data transfer and will help us in using wireless docking stations. This will reduce the cost of backhaul as we will be removing the wires. The issues with 60GHz spectrum are its smaller range receivable to high fading, as the wavelength is small and then it causes blockage collectible to concrete walls 2.We can also see from the figure 2. that the effect of oxygen in the atmosphere at 60GHz is high and causes atmospheric absorption of the millimeter wave. These are some of the limitations of 60 GHz band which are being looked at like the iss ue of absorption by oxygen can be reduced by using band Figure 2. High Atmospheric absorption at 60GHz. 1(ii) Millimeter wave in 5G The proposed band for 5G is 28GHz and 38GHz which falls in the locality of millimeter wave. This is going to help in increase the data rate. The proposed data rate is nearly 20Gbps which is nearly 20 measure that of 4G 8. Millimeter waves can travel smaller distances as the wavelength is small which causes high attenuation due to atmospheric absorption. This can be mitigated by using the model of small cells in our network. Cell size can be up to 200 meters.Figure 3. Attenuation Due to Heavy Rainfall. 1Figure 3 shows the attenuation due to heavy rainfall of 25 millimeter/hour for a 28GHz band for 1 Kilometer cell size i.e. 7db which will be only 1.4db for a cell size of 200 meter 1.2. Beamforming(i) Directional Beamforming in 802.11ad In directing beamforming, the signals are directed to the think receiver. It has been introduced instead of using a n omni way of lifeal feeler which used to send the beam in all the directions reducing the power of the signal. barely it is highly windy to use highly-directional transmissions as there is a high chance of attenuation due to blockages. This can be prevented by using willing assimilate control. MAC mechanisms are also affected due to the Highly directional communications such that the devices are not able to know that there is some other communication going on which increases the chances of smasher. Golay sequences are used to reduce these chances of collisions. Golay sequences are the complementary sequences and help in synchronization and automatic gain control that in turn helps in attaining a throughput of 27.5Mbps thus making Management frames more efficient. Sum of out-of-phase Autocorrelation coefficients for Golay sequences being zero reduces the take aim of side lobes which in turn helps in reducing the chance of collision 2.(ii) Adaptive beamforming in 5G Beamforming is a concept in which we change the specific weights at the antenna aim such that we direct the signal to a specific area by concentrating the power in the main lobe and reducing the power of signals in the side lobe. This will increase the throughput and hence will improve the user experience. In adaptive beamforming, the enthral is used in an efficient manner which also helps in reducing the issue of interference. This can be achieved by using the concept of scheduling in different base stations. This can be used in a precise interesting manner in 5G, and it will also help by improving the coordination amongst various eNodeBs. Hence the concept of adaptive beamforming will make the 5G network faster and more efficient 9.3. MIMO(i) Multiuser-MIMO (MU-MIMO) in 802.11ad At physical layer level 802.11ad works in two modes i.e. OFDM and iodine carrier mode. MIMO is used for diversity in communication. In multiuser MIMO for 802.11ad, we use a matrix of a minimum of 2X2 (2 receiver antennas and 2 vector antennas). We can send signals to 2 or more users at one time with a very(prenominal) high throughput because we are employing OFDM. Previously we were employing only ace user-MIMO wherein we used to send multiple signals to only one user. No doubt it gave high speed, but we were not able to use the limited unlicensed spectrum efficiently. Thus, with the advent of Multiuser-MIMO, the problem of low efficiency has been reduced 2 10.Figure 4. choke up diagram of Transmitter in MIMO 10.From figure 4 we can see how the data is displace using MIMO technique. Here firstly data is sent to the scrambler. later on scrambling the data, it is encoded by the LDPC (low-density parity-check) encoder for tone interleaving. After interleaving the OFDM processed data we apply Inverse Fast Fourier Transform (IFFT) on the data. Finally, we add a ram fragmentize interval to protect the sent data 10.(ii) Massive MIMO in 5G 5G will be using massive MIMO technique that will involve a large number of antennas and the number will more than 10 times larger than previous networks. This will not just give a high amount of beamforming gains but will also increase the capacity of the network. But there is a catch here. The increase in a number of streams will increase the overhead of pilot signals, and because of this, we will use some part of our spectrum. Also, there is an increase in the complexity if we use a high number of antennas. The solution to this overhead is that we can use Non-Linear Estimators and small cells which will help in reducing the effect as at high signal-to-interference-plus-noise ratio (SINR) the effect of errors in the signal is very less 4.III. MAC Layer enhancementsHere are some of the enhancements at the MAC layer of 802.11ad and 5G1. Beamforming Training in 802.11ad Beamforming training is a part of directional beamforming in which we select a pair of receiver and transmitter sectors so that the network can be perfectd and we c an get the scoop up reportage.Figure 5. Sector training in Transmitter and Receiver antenna 2.Figure 5 shows the sector training process. This is done is three phases. In the first step, we try to find the best transmitting antenna. In the second step, the training of only those transmitting and receiving antennas happens for which the transponder thinks are the best for the network. In the ternary step, various weights for the antennas are adjusted according to the changes in the channel so as to get the maximum level of Signal to Noise proportionality which will thus be able to get the best coverage for the network. Hence the process of Beamforming training for 802.11ad is completed 2 3 7.2. Contention-Based Medium Access in 802.11adIn IEEE 802.11 standards, enhanced distributed channel approach highroad (EDCA) is used for contention-based Medium access. But there is an issue of deafness that nobbles when we use the contention based metier access and directional beamforming together. This can be reduced by using Beamforming training wherein we select the best transmitter and receiver antenna for the communication. Chances of collisions are increased due to deafness because carrier sensing ability is reduced. Multiple Network allocation vector (NAV) timers are used at the MAC level. Here the channel is allocated only if the NAV is zero and will not be allocated in case the NAV is non-zero. The concept of NAV for the contention window in 802.11 standards has been used previously as well. Using this concept will enhance the capacity and efficiency of 802.11ad and will be different from previous standards as it uses direction beamforming 2.3. can-do canal Time Allocation in 802.11adDynamic channel time allocation is a polling based allocation of resources in 802.11ad at the MAC layer. The polling is done not just for one frame but for a specific time chunk of the channel. The issue of deafness is avoided due to personal basic service set (PBSS) control point/access point (PCP/AP) that reduces the chance of a collision as PCP/AP knows the path of transmitting antenna. The process of Dynamic Channel time allocation is explained in Figure 6. It shows the Beacon header interval (BHI) can be used in dynamic scheduling. Firstly, a channel is gained by the PCP/AP for the polling frames that are sent to their respective stations. Service period requests (SPRs) are used to apply a specific channel time for their respective communication. Communication can be between Station (STA)- STA or STA Access Point (AP). Channel protection points act as the guard time between two allocated channel times adding reliability in communication 2.Figure 6. Dynamic Channel Time Allocation 2.4. Full- convert MAC Protocol in 5GAt Physical layer level, Full-Duplex must reduce the use spectrum making the communication efficient. At MAC layer level the protocol must be defined such that it optimizes the network and reduces the chances of collision. The problem of a hidden node due to highly directional communication can also arise just like it used to happen in the case of WiFi standards. We can use the concept of Request to steer / Clear to Send (RTS/CTS) which was used in WiFi standards being a half-duplex communication. For 5G we will be using full-duplex clear-to-send (FCTS) instead of just the CTS which was used in WiFi i.e. a unidirectional communication. Figure 7 shows the channel allocation for communication between Node A and Node B. Firstly RTS is sent from Node A to check if there is the availability of the channel. After that there is a briefly Interframe Space (SIFS) for which we need to wait for FCTS from Node B. Now being a bidirectional communication (Full-duplex) an FCTS is sent by Node A as well which makes it different from WiFi standards. After another SIFS interval, the channel is allocated, and there is a bi-directional communication between Node A and Node B. After the channel time allocated is complete, there i s a small SIFS before ACK (Acknowledgement) which is unploughed and this ACK shows that the channel has been released 11.Figure 7. Channel Allocation in Full Duplex 5G between Node A and Node B 11.5. Device-to-device communications in 5GIt is currently a part of LTE-A Release 12 of the 3gpp standards. Device to device (D2D) communication will be an inter-communication between the devices that will use 5G. there is no need to route the data from the 5G base station in D2D communication. The devices will use the same spectral resources as the 5G network. Thus, we must optimize the network to meet the requirement of the users. This will improve the spectral efficiency of the network and will increase the capacity as well. For D2D communication the devices should be in proximity. This can be very useful in case of Autonomous vehicles such as driverless cars which can communicate with each other and thus protect the passengers. D2D communication can occur in two ways. The first way is that one of the UE (User) can send a stagger signal about its availability and what it can offer. The discoverer UE if interested in the characteristics of the programmeing UE establishes a connection. The second way is that one of the UE will broadcast its requirements and the UE which meets these criteria can establish a connection with this UE 12.IV. ConclusionThis paper has have light on the most recent enhancements taking place in 802.11ad and 5G. The paper has addressed the issue of spectral crunch and how these two technologies will cope up with this issue in the near future. The enhancements introduced in the paper have opened the way for the two technologies to interoperate such that the user can get 5G connectivity when outside and 802.11ad connectivity when inside their homes. Convergence of these two technologies will be made easy not just at the Physical level but at the MAC level too. At physical layer level, we have seen the use of mm-wave and directional beamformin g, and at MAC layer level, we have seen full-duplex communication using RTS/CTS in 5G which will increase convergence. Hence, the convergence of these two technologies will increase the capacity as a lot of wise spectrum will be released.V. References1 T. Rappaport, S. Sun, R. mayzus, and H. Zhao, Millimeter Wave Mobile Communicationsfor 5G cellular It Will Work IEEE Access, pp. 335-349, 2013.2 T. Nitsche et al., IEEE 802.11ad Directional 60 GHz Communication for Multi-Gigabit-per-Second Wi-Fi, IEEE Commun. Mag., vol. 52, no. 12, Dec. 2014, pp. 132-41.3 H. Shokri-Ghadikolaei, C. Fischione, P. Popovski, and M. Zorzi, Design aspects of short-range millimeter-wave networks A MAC layer perspective, IEEE Netw., vol. 30, no. 3, pp. 88-96, May 2016.4 V. Jungnickel, K. Manolakis, W. Zirwas, B. Panzner, V. Braun, M. Lossow, M. Sternad, R.Apelfrojd and T. Svensson, The Role of Small Cells, Coordinated Multipoint, and MassiveMIMO in 5G, IEEE Commun. Mag., pp.44-51, May 2014.5 R. new wave Ne e, Breaking the Gigabit-per-second barrier with S02.11AC, IEEE Wireless Communications, vol. IS, pp. 4-4, April 2011.6 S. Parkvall, et al., LTE-Advanced Evolving LTE Towards IMT-Advanced, in IEEE Proc.Vehicular Technology meeting, Sept. 2008.7 E. Perahia and M. X. Gong. Gigabit wireless lans an overview of IEEE 802.11 ac and802.11ad. ACM SIGMOBILE Mobile Computing and Communications Review, 15(3)23-33,2011.8 M.2083, Recommendation ITU-R, IMT Vision framework and overall objectives of thefuture development of IMT for 2020 and beyond, September 2015.9 S. Chen, S. Sun, Q. Gao and X. Su, Adaptive Beamforming in TDD-Based MobileCommunication Systems State of the Art and 5G Research Directions, in IEEE WirelessCommunications, vol. 23, no. 6, pp. 81-87, December 2016.10 X. Zhu, A. Doufexi, and T. Kocak, Throughput and coverage performance for IEEE802.11ad millimeter-wave WPANs, in Vehicular Technology Conference (VTC Spring), 2011IEEE 73rd, 2011, pp. 1-5.11 X. Zhang, W. Cheng, and H. Z hang, Full-duplex transmission in PHY and MAC layers for5g mobile wireless networks, Wireless Communications, IEEE, vol. 22, no. 5, pp. 112-121,2015.12 Z. Ma, Z. Zhang, Z. Ding, P. Fan, and H. Li, Key techniques for 5G wirelesscommunications network architecture, physical layer, and MAC layer perspectives, Sci. ChinaInf. Sci., vol. 58, no. 4, pp. 1-20, 2015.