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- Towards 5G: A Photonic Based Millimeter Wave Signal Generation for Applying in 5G Access Fronthaul
- 5G Development in China: From Policy Strategy to User-Oriented Architecture
- Challenges Grow For 5G Packages And Modules
Lie, J. Mayeda, Y. Li, J.
Towards 5G: A Photonic Based Millimeter Wave Signal Generation for Applying in 5G Access Fronthaul
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In this work, a photonic based simple and robust method for generating millimeter waves applicable in 5G access fronthaul is presented. For the purpose of wireless transmission for 5G application the required antenna is designed and developed. The total system performance in one small cell was studied and the error vector magnitude EVM of the system was evaluated.
Due to fast revolution in mobile technology, wireless technology has been evolving from 1G to 4G. Currently researchers are working on defining next generation of wireless communication, i. Emphasizing on small cell concepts, network speed and capacity enhancement and introducing new communications technologies are among the most important announcements about future 5G 2.
Improving the speed and capacity is required to make the communication for potentially billions of wireless devices feasible. To support the combination of small cells and mm-wave radio for future 5G access, fiber-optic communication plays an important role in both the backhaul and fronthaul networks. As can be seen from Fig. On the other hand, high-speed and convenient mm-wave and small cell WAN is utilized. For generating the high-frequency mm-wave electrical signals, using conventional electronics becomes less financially attractive, therefore, there is a high concern to directly generate mm-wave signals in the optical domain.
Essentially, a photonics based mm-wave is a laser beam consisting of two or more coherent longitudinal modes with frequency spacing equal to the wanted mm-wave. As the longitudinal modes beat with each other in the photodiode, the required electrical mm-wave could be generated. The generation of microwave signals from optical sources has long been a substantial area of interest due to its large potential for a variety of applications in communications 7 , 8 , 9 , 10 , A wide variety of techniques have been demonstrated for optically mm-wave generation, e.
There is also some methods based on an optical frequency combs OFC that is generated by i. Since the two longitudinal modes generated by a dual-mode laser or two separate lasers have low coherency, the mm-wave generated by their beating has poor spectral purity 31 , While mode locked lasers can generate a wide bandwidth frequency comb, they suffer from cavity complexity and lack tunability of the FSR due to a fixed cavity length.
Moreover, the optical linewidth of the individual comb lines may be relatively large and the imperfect phase coherence between two optical tones can cause significant phase noise on the generated mm-wave signal The longitudinal modes generated by the nonlinear effects have higher coherency, but higher pump powers are required and their conversion efficiencies are low Moreover, since the Brillouin frequency shift is fixed in the fiber, the generated optical mm-wave is frequency limited In case of EM, modulators have large insertion losses particularly when cascaded.
Coupled with the modulation efficiency and the instability induced by bias drift, the use of the EM technique can be complex Dual wavelength fiber laser DWFL is one of the interesting approach to generate radio frequency RF signals at mm-wave frequencies 37 , 38 and terahertz sources 39 , Erbium doped fiber EDF is the most commonly used gain medium in fiber laser setup in regions of 1. However, strong mode competition induced by the homogeneous broadening 41 has become the main challenge to achieve stable multi-wavelength oscillation in room temperature.
Achieving dual wavelength generation in the 1. Various methods have been proposed to realize the multi-wavelength operation at room temperature by reducing cross-gain saturation and suppressing mode competition. These include polarization hole burning effect 45 , frequency-shifted feedback 46 , cascaded stimulated Brillouin scattering 47 , four wave mixing 48 , etc.
Recently, the authors have demonstrated a tunable spacing dual wavelength using a photonic crystal fiber PCF as a Mach-Zehnder interferometer utilizing a polarization dependent loss PDL effect This DWFL shows high power stability with a very narrow linewidth. The use of PCF brings advantages of flexibility and wavelength-dependent characteristics, which make the material almost an ideal choice as a wavelength selective filter for EDF Consequently, the RF signal generated by the proposed setup is tuneable, simple and more stable compared to the other discussed methods.
This has not been reported before and the information would be of substantial benefit to the scientific and engineering community in the sense that it would allow for the development of a compact and robust dual-wavelength source that can be easily and safely used to generate RF radiation in real-world settings. The configuration of the DWFL system in 1. The LD is directed into the fiber laser ring cavity through a WDM to provide excitation to the gain medium.
TBPF is used to limit or confine the oscillation of dual wavelength laser in a narrow spacing. The isolators are used to assure unidirectional operation of the laser as to achieve a more stable lasing condition.
The PC is inevitably exploited to adjust the polarization of light propagating inside the ring cavity. The micrograph of the PCF cross-section structure is shown in the inset in Fig. The PCF surrounded by air holes with 5. The coupler is used to direct part of the laser power out of the laser cavity for measurement, analysis and application. The TBPF acted as a window to tune the generated dual wavelength output and had specifications of 0.
Figure 3 a shows the experimental result of the DWFL with 0. The displacement of the output lasing can be achieved by fine tuning of the PC due to the polarization dependence of the laser inside the ring cavity. The adjustment of the PC will rotates the polarization states and allows continuous adjustment of the birefringence within the ring cavity to balance the gain and loss of the lasing wavelengths.
By achieving dual wavelengths laser with similar peak powers, a stable DWFL can be obtained. The unique properties of PCF, such as wide range single mode operation, dispersion flexibility and large mode area, have been investigated recently 52 and the inherent flexibility in particular puts PCF in contention for use as an interferometer. Interferometers employing PCF also can be wavelength-selective filters 50 due to the wavelength-dependent characteristics afforded by PCF.
The first collapsed region served to diffract the traversing fundamental mode and consequently allow core and cladding modes to become excited within the few modes PCF section. A portion of the fundamental core mode can be coupled to a single or several cladding modes in the PCF.
Phase shifting within a physical length, L, of the PCF is a product of dissimilar effective refractive indices of core and cladding modes. As the effective refractive index of the cladding is smaller than that of the core, separate optical paths that correspond to arms of the Mach-Zehnder interferometer can be achieved.
The fundamental and cladding modes accumulate a phase difference along the PCF due to different phase velocities and this phase difference depends on the length of PCF and the wavelength of the guided light. Cladding modes recouple to the core mode upon reaching the second collapsed area of the PCF. Since the phase difference and the phase velocities are wavelength dependent, the optical power transmitted by the interferometer will be minimum at certain wavelengths and maximum at the others.
The optical paths established via the core and the cladding modes behavior within the PCF play the role of arms of a Mach—Zehnder interferometer and the collapsed points perform as couplers that split or combine light in the interferometer arms. The microwave generation is subsequently determined by connecting the dual-wavelength output to the photo detector and taking measurements with the RFSA.
The RF spectrum is shown in Fig. Considering the limited data rates offered by current wireless LAN The frequency drift associated with these transceiver devices is an important factor in specifying frequency band requirements.
Noting the above, there is a need to avoid interference being caused to adjacent frequency bands due to frequency drift of equipment operating in the Therefore, here, the signal stability is investigated by scanning the RF spectrum for every ten minutes. The RF power and frequency stabilities are recorded as shown in Fig. It is found that the frequency drifts between The carrier frequency can be further stabilized by placing the fiber spool in a temperature controller or using polarization maintaining fiber PMF.
RF power stability is important in the implementation of oscillators and carriers. Fluctuations in the millimeter wave power can only be reduced with the enhancement of laser stability. The measured power is low due to the bandwidth limitation of the photodetector. The MCAA shows broader impedance bandwidth and lower cross-polarized radiation as compared with the conventional microstrip grid array antennas. The MCAA is designed not as a travelling-wave, but a standing-wave antenna.
As a result, the match load and the reflection-cancelling structure can be avoided, which is important, especially in the millimeter-wave frequencies. The structure of designed antenna is presented in Fig. Dimensions are optimized by using parallel parametric studies and tabulated in Table 1. Proposed antenna has a gain of In this design not only high gain with an acceptable bandwidth around 7.
Measured S 11 versus frequency is shown in Fig. Figure 7 shows the system design. Then in order to utilize the generated carriers in 5G application we used the OFDM signal to be transmitted in a 5G small cell.
As shown in Fig. The optical filter with a centre frequency of Increasing the number of channels in optical communication systems will eventually result in the usage of optical signal demultiplexing components with greater values of optical attenuation.
Additionally to this, when transmitted over long distances, the optical signal is highly attenuated and therefore, to restore the optical power budget it is necessary to implement optical signal amplification.
At the choice of signal amplification method for the wavelength division multiplexing WDM systems the preference is given to the class of EDFAs. These amplifiers are low-noise, almost insensitive to polarization of the signal and can be relatively simply realized To ensure the required level of amplification over the frequency band used for transmission it is highly important to choose the optimal configuration of the EDFAs, as the flatness and the level of the obtained amplification and the amount of EDFA produced noise are highly dependent on each of the many parameters of the amplifier.
The down-converted signal is further amplified in the frequency range of 0. Baseband digital signal processing including one-tap equalization, demodulation, demapping and error vector magnitude EVM computation are performed offline. The EVM is defined as follows:. Here, N is the number of QAM symbols In the second case shown in Fig. With an increase in the wireless distance, the free-space path loss causes degradation of the EVM performance.
5G Development in China: From Policy Strategy to User-Oriented Architecture
When deployed, 5G networks should deliver more speed and capacity to support massive machine-to-machine communications and to provide low-latency delay , high-reliability service for time-critical applications. Based on trials to date, 5G networks are starting to demonstrate high performance in different scenarios such as dense urban areas and indoor hotspots. With these ambitious goals, 5G networks face considerable challenges. The increased capacity and data rates promised by 5G require more spectrum and vastly more spectrally efficient technologies, beyond what is currently used in 3G and 4G systems. Some of this additional spectrum will come from frequency bands above 24 GHz, which pose considerable challenges. The first challenge refers to the intrinsic propagation characteristics of millimeter waves. These radio waves propagate over much shorter distances than those of medium- between GHz and low- below 1 GHz frequency bands.
The shift to 5G wireless networks is driving a need for new IC packages and modules in smartphones and other systems, but this move is turning out to be harder than it looks. In addition, 5G devices will require an assortment of new technologies, such as phased-array antennas and antenna-in-package. Testing these antenna arrays remains an issue with 5G. The antenna, which is used to transmit and receive radio signals, is separate and not bundled in the module. The big change occurs in fifth-generation wireless networks, or 5G , which is a new wireless technology with faster data rates than 4G.
At Ericsson, our 5G is made for innovation. We are proud to be supporting our pioneering partners with their 5G switch. Ericsson is the first company to launch live commercial 5G networks on four continents. Our Core solutions are supporting 2. And thanks to our ongoing interoperability engagements with six out of six chipset vendors, our 5G technology is evolving continuously to support a variety of 5G devices. That way, we can cater to the wide-ranging 5G use cases of today and tomorrow. Because 5G is much more than speed and far beyond a network upgrade — the potential for new revenue streams coming from consumers is limitless.
A survey of different enabling technologies of 5g network is provided afterwards. Finally, the 4G networks are IP based network integrating all kinds of existing networks and The main difference was that it utilized time division multiple cancellation before it passes through analog to digital converter.
Challenges Grow For 5G Packages And Modules
In telecommunications , 5G is the fifth generation technology standard for broadband cellular networks , which cellular phone companies began deploying worldwide in , and is the planned successor to the 4G networks which provide connectivity to most current cellphones. All 5G wireless devices in a cell are connected to the Internet and telephone network by radio waves through a local antenna in the cell. The increased speed is achieved partly by using higher-frequency radio waves than previous cellular networks.
In telecommunications , 5G is the fifth generation technology standard for broadband cellular networks , which cellular phone companies began deploying worldwide in , and is the planned successor to the 4G networks which provide connectivity to most current cellphones. All 5G wireless devices in a cell are connected to the Internet and telephone network by radio waves through a local antenna in the cell.
The development entails both technological advancement and social interaction. This paper analyzes 5G development and its significant shift from a strategy policy to a user-oriented development showing the coplay of technology and society in China. Based on this theory, relevant proposals are recommended for future technical development and industrial regulation. Also, to increase the throughput and spectrum efficiency, channel assignment and load balance are considered.
Welcome to our pick of the best mobile hotspots for 4G and 5G mobile data connections around today. The best mobile hotspots for 4G and 5G allow for several devices to connect to one or more data SIMs — usually 4G ones — to surf privately and safely. Much like a smartphone's SIM card , these data-only deals allow you access to the internet in complete security. That means no more having to connect to free or open Wi-Fi hotspots, which can put your security and privacy in danger.
In our previous article, we talked about the overall 5G chipset market. In this article, we will particularly discuss the top 5g chip makers leading the 5G semiconductor market. There are many companies participating in 5G chipset manufacturing, however, there are only four companies that are doing exceptionally well in the current times.
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