Millimeter Wave MIMO Systems for 5G Access Networks

Guest post by Faris Alfarhan*

Cellular NetworkConventionally, millimeter wave (mmW) frequency bands have been either largely overlooked or treated solely as real estate for wireless backhaul and personal indoor networks. That is mainly due to higher atmospheric attenuation loss, penetration losses, and increased absorption and scattering in rainy conditions. However, recent measurements indicate good outdoor short range coverage – of 200 meters on average – when using directive antenna beams, even when radio line of sight conditions are not met [1-3]. The propagation characteristics of mmW bands vary considerably depending on whether LOS or NLOS conditions are present. Since mmW signals experience low diffraction due to their small wavelength, LOS signals propagate in conditions similar to free space (a path loss exponent of 2 on average). NLOS signals, on the contrary, experience more significant losses and hence a pathloss exponent of 5.7 on average [3]. However, the NLOS pathloss exponent is significantly reduced when directing the Tx and Rx antenna beams towards each other. In order to overcome the increased pathloss at mmW frequencies, directional beamforming or beamsteering is used to generate narrow beams towards users. Since the required antenna size is inversely proportional to the operating frequency, mmW antenna arrays could encompass as much as 64-256 antenna elements at the base station and 4-12 elements on a mobile device. For example, the required antenna element length is about 0.5 cm at 28 GHz,whereas it is about 20 cm at 700 MHz. Figure 1 shows measurement results for the maximum coverage distance of a mmW systems operating at 28 GHz as a function of the pathloss exponent and the combined Tx-Rx antenna gains, where acceptable coverage is deemed to have an SNR of 10 dB and higher. Read more of this post

It’s All Too Good To Keep Talking About The Capacity Problem

TalkingThe capacity problem is at the heart of everything said about the wireless industry. Everybody loves to talk about this problem. To start, it is easy to give examples of exploding data consumption forecasts or quote numbers on mobile applications such as Facebook, Twitter , Instagram and many others. I suspect that the capacity problem makes for a convenient argument for the different players in the mobile value chain to get what they want: it is a nice problem for everyone to have. For service provider side, it is the key to more frequency spectrum which further enhances increases their position in the market and consequently their value.  For solution vendors it gives them the opportunity to raise money, fund development projects and present forecasts for high revenues. For regulators it gives them the opportunity to sell spectrum and raise money. So everyone can benefit from the capacity problem, or so it seems. Read more of this post

Should Licensed Spectrum be Allocated to IoT Applications?

IoT ConnectivityA mix of connectivity technologies combines to enable the Internet of Things. These technologies can be complementary or competitive in nature. Determining which fits and which does not starts with the application use case and the user requirement. For most IoT applications there is no need for broadband connectivity. Rather, what is required is a reliable connectivity to transmit intermittent data cost effectively. This includes low maintenance and serviceability and low power consumption. To address such applications, new standards are emerging for low power wide area (LPWA) connectivity with operations in unlicensed bands such as 900 MHz or TV whitespaces. But that leaves connectivity subject to external interference that cannot be managed. Hence, should there be a dedicated spectrum for IoT applications? Read more of this post

The IoT Value Chain: Where’s the Value?

IoT Internet of things$19 Trillion is a lot of money. That’s the value Cisco expect the Internet of Things (IoT) market will generate over the next 10 years. Compare with annual world GDP of 75 Trillion, IoT will make for about 2%. Not bad. In terms of devices, the talk is for 50 billion connected devices in 2020, other estimates from ABI put the number at 30 billion and JP Morgan feels more like 75 billion in 2020; no matter, there will be a lot of devices! With this context, no wonder companies are salivating at the opportunity IoT brings about for new revenues streams and profits. But where will the value be and how can it be captured? This question is surely on the mind and lips of executives and the subject of discussion in many boardrooms. Read more of this post

Defining the Innovation Band and Shared Spectrum Access

3.5 GHz Shared Spectrum RulesSpectrum sharing rules for the 3.5 GHz band in the US are beginning to take shape. While there are still some important aspects to define, the broad lines have been drawn for the Citizens Broadband Radio Service (CBRS). The process of fine-tuning the rules will continue following the April Further Notice of Proposed Rulemaking (FNPRM) (comments are due July 14th and reply comments by August 1st). The proposed rules will have a three-tiered spectrum sharing scheme in 3550 – 3650 MHz between Incumbent Access, Priority Access License (PAL) and General Authorized Access (GAA) users. Furthermore, there door is open to roll into this band the 3650 – 3700 MHz band which today operates on a non-exclusive licensed basis. Read more of this post

Raising the Stakes in 3.5 GHz: LTE-Advanced Achieves 1 Gbps

1Gbps LTE-AThe 3 GHz frequency bands stands at the upper limit of what is considered today as viable spectrum for mobile communications. But bands 42 (3400 – 3600 MHz) and 43 (3600 – 3800 MHz) are not only the ‘last frontier’, but more importantly, they provide the widest spectrum of any other band (200 MHz). Additionally, the relatively short wavelength is perfect to enable advanced antenna system technologies based on beamforming and massive MIMO techniques. Couple these with the limited range of propagation that limits interference and the 3.5 GHz band becomes an interesting proposition for capacity starved operators. Read more of this post

Small Cells Progress Report – Challenges and Opportunities.

Small cells I have just released a new research report on the progress of small cell deployments in collaboration with ExelixistNet:  “Small Cell Ecosystem: Challenges and Opportunities.” The report examines mobile operators’ plans and deployment strategies of small cells and backhaul solutions along with vendor and technology preferences. The research is based on experience gathered by operators from market trials of small cells and wireless backhaul solutions conducted to evaluate the ecosystem deployment readiness and impact of small cell roll-out on operator financials and network performance. Read more of this post

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