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Is the Personal Cell Technology for Real?

24 Feb


The media is abuzz with the news of the pCell wireless technology – after all, it’s not too often that someone comes out and claims to have a technology that will change the world! For now, too little has been revealed on this technology, which is understandable for a startup.  The aura of mystery is necessary to fuel the hype machine. So, what can we deduce from what little has been revealed? And, what are the prospects of such technology? I will outline here a few thoughts to start this conversation and I look forward to your observations and opinion.

Here are some pointers:

1- Centralized baseband processing: the baseband processing for the pCell is centralized in one location. Centralization enables coordination of distributed remote radios that are placed in different locations. This in turns enables joint processing of signal streams which are transmitted and received by the distributed radios. The principles are similar to Cloud RAN technology where the baseband is pooled and virtualized (doubtful that this is the case yet for the pCell). Joint processing enables features like network MIMO and coordinated multipoint which brings second feature below. For this to work properly the connection between the distributed radio and baseband needs to have high capacity because it transports IQ symbols and it requires very low delay (tens of microseconds) and low jitter (tens of nanoseconds).

2- Network MIMO: LTE base stations feature MIMO antenna systems where on the downlink multiple (mostly two today) data streams are transmitted to the user who’s equipped with two antennas to receive these streams. Provided the signal quality is good, and there’s sufficient isolation between these streams (uncorrelated streams), the receiver will be able to decode each stream and extract the data. This provides a 2x capacity increase. But what if the multiple antennas were not in one location, but are rather distributed across different points in the network? This is possible when the baseband is centralized and connected through high-speed fiber connection to remote radios. The result is similar. The fact that with the pCell the number of antennas N (or antenna locations) needs to match the number of users M to increase capacity by that number is indicative of some form for network MIMO.

3- Beamforming: The demonstration of the pCell shows what Perlman calls a ‘bubble’ around the receiver (1 centimeter in size as he claims). This is indicative of some type of beamforming. There are different ways in which MIMO and beamforming can be combined so the implementation of these features is what matters and, of course, not revealed.

The basic description of the pCell technology and particularly what is termed ‘DIDO’ or distributed input distributed output, is fundamentally the use of uncorrelated multipath to create orthogonal wireless communication channels between a set of transmitters and receivers. In such a case, there is a limit on the number of supported users and their respective capacity that is proportional to the number of antennas, which in this case, includes the number of distributed nodes. In short, there are practical limits to capacity which cannot increase ‘forever’ as portrayed in the media.

With this context, is the pCell a breakthrough in technology? I don’t think so. The principles and mathematics are understood. What is new is that someone actually built and tested it. Furthermore, implementing the technology in practice will be highly dependent on the economics of the link between the central processing and remote radios (called fronthaul). Other practical limitations include the cluster size (number of nodes and antennas that can work in unison) which will impact capacity. To support hundreds of users as LTE does today, there will be no escape, for the time being, from sharing time and frequency resources as it is done now. This is not to take away from what has been accomplished – but to put matter into perspective.

So, these are some of my thoughts to kick start this conversation… I look forward to your observations and opinion!




5G Service On Your 4G Phone?

24 Feb

Images: Artemis

A new San Francisco-based start-up, Artemis Networks, announced today that it plans to commercialize its “pCell” technology, a novel wireless transmission scheme that could eliminate network congestion and provide faster, more reliable data connections. And the best part? It could work on your existing 4G LTE phone.

If it proves capable of scaling, pCell could radically change the way wireless networks operate, essentially replacing today’s congested cellular systems with an entirely new architecture that combines signals from multiple distributed antennas to create a tiny pocket of reception around every wireless device. Each pocket could use the full bandwidth of spectrum available to the network, making the capacity of the system “effectively unlimited,” says Steve Perlman, Artemis’s CEO.

First introduced in 2011 under the name DIDO (for distributed input, distributed output), pCell seems almost too fantastic to believe. And no doubt Artemis will have plenty of critics to pacify and kinks to smooth out before operators like Verizon or AT&T pay serious attention. But there are at least a couple reasons why the idea might have some real legs.

First, it’s an elegant solution to a persistent global problem. Wireless traffic ismore than doubling each year and cellular operators are struggling to keep up with that growth. “Demand for spectrum has outpaced our ability to innovate,” says Perlman, whose past entrepreneurial ventures include the cloud-based gaming service OnLive and WebTV (now MSN TV), which he sold to Microsoft in 1997.

The reason isn’t for a lack of ideas. The wireless industry is pursuing plenty of them, including small cellsmillimeter-wave spectrum, fancy interference coordination, and multiple antenna schemes such as MIMO. But Perlman thinks many of these fixes are just clever kludges for an outdated system. The real bottleneck, he argues, is the fundamental design of the cellular network. “There is no solution if you stick with cells,” he says.

What’s wrong with cells? In a word: interference. Base stations and wireless devices must carefully coordinate their transmission power and spectrum use so that they don’t jam one another’s signals. This ability to divide spectrum resources among many users has been at the heart of mobile systems pretty much since they emerged in the 1980s. It’s also the reason why data rates tend to plummet when many users try to use the same cells, such as in New York City’s Times Square.

Artemis is approaching wireless transmission in a completely new way. Basically, its pCell technology could allow each wireless device to use the full bandwidth of the network regardless of how many users join and how tightly they’re packed together. It’s as if your phone were continuously the sole user of its own personal cell. Hence the name pCell.

To understand how such a system would work, let’s start with the basic set-up. To deploy the technology, an operator would first need a cloud-based data center—a rack or many racks of connected servers that would do all the heavy computation for the system. The operator would then need to install radio antennas where its customers are located, such as in homes, businesses, and city streets. Although these access points might look like small cells(Artemis’s, pictured below, are about the size of a hat box), they’re unlike ordinary base stations. “They’re dumb devices,” Perlman says, serving merely as waypoints for relaying and deciphering signals. Each one could be placed anywhere that’s convenient and would link back to the data center through a fiber or wireless line-of-sight Internet connection.

Now suppose that your phone wants to connect with this pCell network. It would simply send out an access request as it normally does. And all of the “dumb” antennas in your vicinity—let’s say there are 10 of them—would pick up those signals and relay them to the data center.

That’s where things get interesting. Say, for example, you play a YouTube video. The pCell data center would request the video from Google’s servers, and then stream it to your phone through those 10 antennas. But here’s the key innovation: No one antenna would send the complete stream or even part of the stream. Instead, the data center would use the positions of the antennas and the channel characteristics of the system, such as multipath and fading, to calculate 10 unique waveforms, each transmitted by a different antenna. Although illegible when they leave the antennas, these waveforms would add up to the desired signal at your phone, exploiting interference rather than trying to avoid it.

And as you move about, and as other devices connect to and drop off the network, the data center would continuously recalculate new waveforms so that each device receives the correct aggregate signal. “There’s no handoffs and one has to take turns,” Perlman says. “You could literally light up a whole city using all the same spectrum.”

If pCell technology does take off in the next few years, it will likely be because it’s compatible with 4G LTE phones. It does this by simulating LTE base stations in software. The data center would use these virtual radios to inform its waveform calculations, essentially tricking an LTE phone into believing it’s connected to a physical base station. “Your phone thinks its the only phone in the cell and is sitting right next to the tower,” Perlman says. The same technique could also work for other wireless standards, such as 3G and Wi-Fi, he says.

So will operators adopt pCell? It’s unlikely that LTE carriers would replace their networks any time soon, even if Artemis’s technology proves to be the “sea change” Perelman believes it is. But its compatibility with LTE changes the game. For instance, operators could deploy pCell antennas in congested hot spots such as airports, sports stadiums, and city centers—places where they’re already investing in new infrastructure. Users could roam seamlessly between the two networks without having to buy new phones or switch service plans.

Artemis says it plans to license pCell to wireless carriers and Internet service providers. The company is now beginning large-scale trials in San Francisco and expects the technology will be ready for commercial rollouts by the end of 2014. It will be fascinating to see how its ambitions pan out.


LTE network speeds, according to the latest OpenSignal report

24 Feb

The United States trails 13 countries when it comes to LTE network speeds, according to the latest OpenSignal report. The report found that average LTE network speeds in this country have declined 32% this year. Australia posted the fastest LTE speeds, with an average download speed of 24.5 megabits per second. Other countries with faster LTE speeds than the 6.5 Mbps posted by the United States were (in order) Italy, Brazil, Hong Kong, Denmark, Canada, Sweden, South Korea, the United Kingdom, France, Germany, Mexico, Russia and Japan.

The United States suffered the biggest decline in network speeds of any country, as operators struggled to keep pace with increasing data downloads. Last year the U.S. ranked 8th in the OpenSignal study, with an average LTE network download speed of 9.6 Mbps.

Many of the nations with faster speeds than the United States do not have as much LTE coverage. Verizon Wireless and AT&T Mobility, which together have roughly 200 million subscribers, are both nearing completion of their LTE roll outs with more than 300 million potential customers covered. Sprint and T-Mobile US both have substantial footprints as well, having recently surpassed 200 million pops covered. “The [United States] performs well on our coverage metric, with the average user experiencing LTE coverage 67% of the time, with Australia, the fastest country, on 58%,” OpenSignal said in a press release.

When it comes to domestic network speeds, T-Mobile US had the best performance among the carriers. The carrier posted average download speeds of 11.21 Mbps, with AT&T Mobility No. 2 at 8.9 Mbps. Verizon Wireless clocked in at 7.8 Mbps and Sprint’s average download speed was 4.2 Mbps. Sprint currently has the least amount of spectrum dedicated to its network at just 10 megahertz in most markets, while the others provide at least double that amount.

The State of LTE

Network operators around the world are working hard to convince their users to make the jump to LTE. The term “4G” acts as a convenient label for marketers to emphasise the superiority of this new standard over its predecessors, but just how standard or consistent is the experience of users on LTE?

The OpenSignal app allows users to contribute to our impartial coverage maps of mobile networks, we took data from those of our 6 million users who have LTE and focussed on their experience of two key metrics: download speed, and the proportion of time spent with LTE access. All data included in this report comes from the second half of 2013.

We found that not all LTE networks are created equal, indeed there is an extremely broad range of experience across both metrics. Only about a quarter of networks surveyed achieve both good coverage and fast speeds; clearly there remains much work before LTE lives up to its full potential.

LTE EPC: Addressing the Mobile Broadband Tidal Wave

24 Feb

The mobile Internet has changed the way people communicate, stay informed, and are entertained. With more compelling services and mobile multimedia computing devices, users are increasingly entering the network and creating an enormous surge in mobile traffic.

To address this new normal, operators must deploy a core network that combines performance with intelligence to meet different traffic demands with an elastic architecture. An intelligent core network allows them to create a robust multimedia environment, enhance and manage the subscriber experience, and monetize network traffic.

Long-Term Evolution (LTE) is the next-generation mobile wireless technology designed to deliver ultrahigh-speed mobile broadband. The primary goals of LTE are increasing bandwidth, improving spectral efficiency, reducing latency, lowering the cost per byte, and enabling improved mobility. This combination aims to enhance a subscriber’s interaction with the network and further accelerate the adoption of mobile multimedia services, such as online television, streaming video, video on demand (VoD), social networking, and interactive gaming.

Radio access solutions are a primary consideration of the LTE deployment strategy, because LTE affects the mobile operators’ most valued asset: spectrum. However, equally important is the multimedia core network.

The Evolved Packet Core: The Next-Generation Packet Core for All Networks

LTE calls for a transition to a “flat”, all-IP core network with open interfaces, called the Evolved Packet Core (EPC). The goal of the EPC is higher throughput, lower latency, simplified mobility between Third-Generation Partnership Project (3GPP) and non-3GPP networks, enhanced service control and provisioning, and efficient use of network resources. Although the EPC has been defined in conjunction with LTE, it is an open next-generation packet core for all networks, including 2.5G, 3G, 4G, non-3GPP, and even fixed networks. In addition, although the EPC represents one of the smallest percentages of overall wireless infrastructure spending, it provides the greatest potential effect on overall network profitability through enablement of new services combined with cost savings from operational efficiencies.

As a result, mobile operators are looking for the best multimedia core solutions to deliver an optimum user experience and migrate to an efficient, intelligent EPC.

Important considerations for the multimedia core network include:

• Support for multiple access network types, including 2.5G, 3G, and 4G; deployment flexibility and network optimization including backhaul

• Smooth and flexible evolution from 2.5G and 3G to 4G

• Massive increase in signaling

• Increased user-plane performance

• Session-state and subscriber management

• Integration of intelligence and policy control at the mobility anchor point

• Security

• Voice-grade reliability

• Reporting, monitoring, accounting, and charging

• Roaming

• Support for multimedia services over the packet switched infrastructure

Cisco is exceptionally well positioned to address these challenges and assist in the migration to an LTE EPC, bringing the products and expertise needed for this evolution.

Cisco ASR 5000 Series Platform

The Cisco ® ASR 5000 Series extended by the Cisco ASR 5500 is elastic; it combines high capacity, high availability, and powerful performance with unparalleled subscriber and network intelligence. Designed for the evolution from 3G to 4G, the Cisco ASR 5000 Series platform is the benchmark for today’s and tomorrow’s multimedia-enabled core network. The platform uses a simple, flexible distributed architecture that supports multiple access technologies, subscriber mobility management, and call-control capabilities, as well as inline services (Figure 1). With its leading-edge throughput, signaling, and capacity, the Cisco ASR 5000 Series can readily support all EPC network functions.

Figure 1. The Cisco ASR 5000 Series in a Multiaccess Multiservice Environment

EPC Network Functions

The LTE EPC performs a series of network functions that flatten the architecture by minimizing the number of nodes in the network. As a result capital and operational expenditures decrease, thereby trimming the overall cost per megabyte of traffic while improving network performance. Cisco provides the functions defined for the LTE EPC, including the following:

• The Mobility Management Entity (MME) resides in the control plane and manages states (attach, detach, idle, and Radio Access Network [RAN] mobility), authentication, paging, mobility with 3GPP 2.5G and 3G nodes (Serving GPRS Support Node [SGSN]), roaming, and other bearer management functions.

• The Serving Gateway (SGW) sits in the user plane, where it forwards and routes packets to and from the eNodeB and Packet Data Network Gateway (PGW). It also serves as the local mobility anchor for inter-eNodeB handover and roaming between 3GPP systems, including 2.5G and 3G networks.

• The Packet Data Network Gateway (PGW) acts as the interface between the LTE network and packet data networks, such as the Internet or IP Multimedia Subsystem (IMS) networks. It is the mobility anchor point for intra-3GPP and non-3GPP access systems. It also acts as the Policy and Charging Enforcement Function (PCEF) that manages quality of service (QoS), online and offline flow-based charging data generation, deep packet inspection, and lawful intercept.

• The Evolved Packet Data Gateway (ePDG) is the element responsible for interworking between the EPC and untrusted non-3GPP networks, such as a wireless LAN.

• Release 8 Serving GPRS Support Node (SGSN), also known as the S4 SGSN, provides control, mobility, and user-plane support between the existing 2.5G and 3G core and the EPC. It provides the S4 interface that is equivalent to the Gn interface used between the SGSN and the Gateway GPRS Support Node (GGSN).

The Cisco Difference

Cisco multimedia core platforms are built to address the needs of the mobile multimedia core market.

Cisco brings a history of innovative solutions that already meet many of the requirements of the EPC, such as integrated intelligence, simplified network architecture, high-bandwidth performance capabilities, and enhanced mobility.

Therefore, Cisco solutions can support 2.5G and 3G today and, through in-service software upgrades (ISSUs), will support mobile broadband functions as LTE networks are deployed. These platforms can support multiple functions in a single node, allowing a single platform to concurrently act as an MME, Release 8 SGSN and SGW, SGW and PGW, or even as a 2.5G and 3G and LTE EPC node. Mobile operators who want a smooth network migration can maximize the return on their investments and offer an exceptional experience to their customers.

Specific key features include:

Network Flexibility:

• Common platform for all network functions

• Integration and colocation of multiple core functions

• Software architecture that enables service reconfiguration and online upgrades

• Evolution from 3G to LTE

• Single operations, administration, and management (OA&M), policy, and charging integration

Superior Overall Performance:

• High performance across all parameters – signaling, throughput, density, and latency

• Linear scaling of network functions and services

• Support for 2.5G and 3G LTE service on any card running anywhere in the system

• Resources distributed across the entire system

Integrated Intelligence with Policy Enforcement:

• Integrated deep packet inspection, service control, and steering

• Value-added inline services

• Integrated policy enforcement with tightly coupled policy and charging

• Support for integrated Session Initiation Protocol (SIP) and IMS functions

• Consolidated accounting and billing

Outstanding Reliability

• No sessions lost because of any single hardware or software failure

• Automatic recovery of fully established subscriber sessions

• Interchassis session recovery or geographic redundancy

• Network Equipment Building Standards (NEBS) Level 3 certification


Although the deployment of LTE RANs receives considerable attention, the EPC has emerged as critical for delivering next-generation mobile broadband services. As such, mobile operators must look for solutions that can address today’s requirements while positioning them for future technologies.

Cisco is focused on the elastic multimedia core network and the challenges it presents to the mobile operator. We have led the industry with intelligent, high-performance solutions that have changed the packet core environment to a true multimedia core network. We will continue to harness this proven experience and expertise to become your trusted advisor and deliver best-in-class solutions that evolve the mobile operator’s network and help deliver on the promise of true mobile broadband.

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