LTE vs WIMAX

WiMAX and LTE will be the next future 4G broadband wireless access technologies. These two technologies aim to provide mobile voice, video and data services by promoting low cost deployment and service models through Internet friendly architectures and protocols.

The WiMAX (IEEE 802.16 standard) comes from IEEE family of protocols. It was developed in US, which is the country with higher implementation and network coverage. The LTE, on the other hand, comes from the 3GPP and it was developed as a European standard. There are lots of differences between these two standards, specially related with the air interface radio aspects, the access modes and protocol aspects.

The latency is one of the most important aspects in real-time multimedia services (Video on Demand and Live Video Streaming such as live tv, broadcast services, videoconference…): the lower the latency is, the better QoS will be. The LTE latency is around 10ms, whereas in WiMAX it is around 50ms. Moreover, WiMAX needs a longer frame overhead, which means higher packet delay.

The battery life of the mobile devices is a key, specially in smartphones and tablets. LTE consumes lower power than WiMAX because of the uplink access technique: LTE uses SC-FDMA which can be interpreted as a linearly precoded OFDMA scheme. This technique consumes lower power than OFDMA, the WiMAX used technique, so it prolonges the handset battery life.

LTE makes possible Internet connections under 350km/h and WiMAX only allows 120km/h. LTE supports handover and roaming with 3GPP networks, which is not easy to do with WiMAX. So, in terms of mobility LTE is also better than WiMAX.

LTE has another key performance advantage: it is better integrated with other cellular technologies, making for smoother transitions between 3G and 4G. Moreover, LTE evolved from 2G and 3G standards (GSM, HSPA+ and UMTS), so today’s infrastructure, protocols and mobile devices will be easily adapted to LTE networks.

Today it seems that LTE will win WiMAX and world mobile operators have started to switch from WiMAX to LTE. Nowadays the amount of subscribers is increasing day by day: USA is the leading of LTE market, first deployments are started on South America this year, european countries started to implement since 2011 and it is expected to be implemented in Russia, India and China.

Advertisements

ISA SP100

The ISA SP100.11a standard centers around the process and factory automation and is being developed by the Systems and Automation Society (ISA). It is used in devices and systems that sense meansure and control industrial processes and manufacturing operation.

ISA 100.11a is a robust, scalable and flexible standard. It provides a low-bitrate and very low power consumption communication with a transparent network management to the user. It allows adaptive routing, multiple network topoligies, addressing system and redundancy levels. Moreover, it uses some mechanisms for granting a sustainable amount of devices in the network, a good spectrum management, coexistence with other networks and reliability in the communications.

EPS=LTE+SAE

The 3GPP Release 8 standard specifies the 4G Evolved Packet System (EPS), which includes the E-UTRAN (access network also known as LTE) and EPC (core network also known as SAE).

SAE

System Architecture Evolution (SAE) is the evolution of the GPRS Core Network. It is a simplified architecture where the intelligence is in the access network instead of the core network. It is an all-IP Network and supports higher throughput and lower latency radio access networks, including E-UTRA (LTE and LTE-Advanced air interface), 3GPP legacy systems (GERAN or UTRAN) and non-3GPP systems (WiMAX or cdma2000).

LTE

The EPS, also known as LTE, is designed to provide high data rates and low latency using a flat, all-IP network architecture. The EPS is standardized to provide all services including mobile broadband data, high-quality voice, and multimedia services.

Downlink peak data rates provided by LTE up to 100Mb/s and 50Mb/s in the uplink. It operates in both TDD and FDD modes and it has a scalable bandwidth up to 20MHz, covering 1.4, 3, 5, 10, 15 and 20MHz. The usage of OFDMA (SC-FDMA in the uplink) and MIMO technic increase spectral efficiency over 3 times.

HSPA+

HSPA+, or Evolved High-Speed Packet Access, is a technical standard for wireless, broadband telecommunication. HSPA+ enhances the widely used UMTS based 3G networks with higher speeds for the end user, which is comparable to the newer LTE networks.

HSPA+ was first defined in the technical standard 3GPP release 7 and expanded further in later releases. HSPA consist on HSDPA (Downlink) and HUSPA (Uplink) which are completely different systems (the only thing they have in common is the HARQ mechanism).

The usage of MIMO technics and 16/64QAM modulation in HSDPA provide higher data rates (14.4Mbps). HSPA+ increases the network capacity and the user data rates because of the better spectral efficiency. Moreover, it reuses UMTS architecture in order to minimize the capital expenditure of the operator, but base stations (NodeB) have more intelligence with RNC functions. The flattened all-IP architecture, where the stations connect to the network via IP, allows a faster and cheaper network.

In Spain, Movistar, Vodafone and Yoigo has commercially launched HSPA+ with speeds up to 42Mb/s in major cities.

Femtocells technology

With the explosion of the Internet connected devices, such as smartphones or tablets, the demand of higher data rates in wireless networks is increasing day by day. Consumers are increasingly sensitive to coverage for both voice and data, especially at home and in the office. Operators need to meet this demand quickly and at a reduced cost-per-bit, which is the main motivation of the femtocell technology

What is a femtocell?

A femtocell, also called home base station, is a low-power access point which is basically used to provide coverage and capacity in home and office environments. The femtocell is a small device connected to the service provider via broadband network (ADSL or cable) and supports simultaneous voice conversations and data services.

When the mobile phone is under the coverage of the femtocell, it switches over from the macrocell to the femtocell automatically. Then, the user has the same services but the connection comes from ADSL.

Architecture

Despite there are different standards and technologies, all broadly conform to an architecture with three major elements:

  • femtocell acces point: connects to the mobile operator network via broadband network.
  • femtocell gateway: aggregates the traffic from different femtocells.
  • femtocell management system & security: manages different home base stations.

Beneffits

For a mobile operator, the attractions of a femtocell are improvements such as:

  • Better coverage and capacity because of the short distance between the transmitter (femtocell access point) and the receiver (mobile phone).
  • Improved macrocell reliability: traffic originating indoors can be absorbed into femtocell networks and the macrocell can redirect its resources.
  • Cost benefits: reduced operating and capital expenditure costs for operators.

Moreover, the femtocell provides to the user:

  • Better quality voice and high-speed data services, such as video streaming.
  • Security mechanism and protocols.
  • Prolong handset battery live because of the lower transmit power.

Deployment of femtocells

Several organizations are working to standardize femtocells technology: 3GPP, Broadband Forum, Femto Forum and Next Generation Mobile Network. The initial priority for standardization efforts was focused on 3G technologies, but nowadays the data rates are still lower than WiFi and that is why the deployment is lower than the operators commitment.

However, with LTE and 4G systems, which are designed to integrate femtocells in their architecture providing higher data rates, QoS and security (better than WiFi), femtocells are going to change the landscape of mobile technology and networking business in the coming years.

SIP protocol

Session Initiation Protocol (SIP) is a signaling protocol used to establish session between pairs. It allows to exchange information about session’s description through the Session Description Protocol (SDP).

The signaling protocol manages the user’s registration and his location. It is also a mechanism to establish and destroy connections end-to-end by some request message. It also routes response from destination to the source in order to ask to the caller.

SIP vs SS7

If we compare the two protocols they are designed for different kind of networks: SIP works on the IP network whereas SS7 in the PSTN networks. Because of that it is not possible to physically replace SS7 with SIP.

SIP applications

The two main applications of SIP are VoIP phones such as softphones and mobile VoIP with DECT protocols. However, the kill application is VoIP, which is the best-performing industry of the past decade and hard VoIP users top 100 million.

SIP competitors

H.323 was created to enable videoconferencing capabilities over a LAN. It was quickly adopted by the industry as a means of transiting voice communication over a variety of IP networks. It was perceived as the biggest SIP competitor, but nowadays the market is divided: H.323 is used in enterprises for video conferencing systems, while SIP is used for Internet telephony voice services.

H.325 is a new multimedia system with significant improvement over legacy SIP and H.323 in the diversity of applications that will enable. Nowadays H.323 is a work in progress but we can predict an important impact of this protocol on the market.

XMPP is an open-standard protocol based on XML language. Nowadays users of Facebook, Google Talk and Windows Live Messenger use this protocol, which means than over 1200 million users are using XMPP. Because of that, SIP is a potentially great competitor of SIP.

Skype is the most popular commercial VoIP softphone which uses a private protocol: the code is obfuscated and some parts are encrypted. Nowadays it has more than 663 million users and several platforms and probably in the next few years that won’t change.

Digital Terrestrial Television (DTTV)

DTTV is digital transmission television broadcast entirely over earthbound circuits. It is transmitted on radio frequencies through terrestrial space using multiplex transmitters to allow reception of multiple channels on a single frequency range (subchannel). The DTTV transmitter broadcast the multiplex, which contains the digitalized and compressed audio and video. To broadcast the video, the DTTV transmitter uses the channel coding to protect the bitstream and the modulator.

The modulation method in DTTV is COFDM where closely spaced orthogonal subcarrier signals are used to carry data. The data is divided into several parallel data streams or channels, one for each sub-carrier. Each sub-carrier is modulated with  either 16QAM or 64QAM  where the last one allows to transmit greater bit rates but it is more susceptible to interference. Moreover, DTTV use hierarchical modulation, where 16 and 64 QAM constellations can be combined in a single multiplex providing a controllable degradation for more important program streams.

DTTV allows to transmit multiple tv channels on a subcarrier, which it means that multiple streams are transmitted on a single frequency range. In the next figure you can see the organization of the spain channels in 2011. As you can see, every multiplex contains different channels: multiplex 55 (545MHz), for example, contains HDvideo (TveHD), 16:9video (Teledeporte), radio (RNE) and data streams with EPG, Teletext and dual language.

The number of channels included in a multiplex depends on the bitrates of that channels. Every multiplex has 20Mbps, so any combination of different channels will be possible to distribute this 20Mbps. The most common bitrates in Spain for the different types of channels are:

  • HD – 8Mbps
  • 16:9 – 5Mbps
  • radio – 320kbps
  • radio – 192kbps

Bandwidth requirements for DTTV over the Internet

DTTV can be delivered with our broadband network, where at least 2Mbps is needed to web-based applications on the computer and 64kbps is required to use landline telephone. For that reason, there’s a limitation on the amount of simultaneously tv/radio channels that we can recieve through our broadband Internet. 


The bandwith requirement for IPTV depends on the number of devices inside the household and it increas with each device. In minimal usage, to recieve an IPTV requires 13Mbps to process in a household. Currently compressed HDTV content can be delivered at a data rate between 8 and 10Mbps, but if the home of the consumer equipped with several HDTV outputs, this rate will be multiplied respectivetly. For that reason, there are a lot of possible combinations with HDTV streams, StandardTV streams, Audio streams, etc.