Self Organizing Network helps in reducing the system overload in an automated way. This new video from Ericsson describes what is SON and how Self Organizing Network will help not only LTE but also in older technologies like 3G and 2G. Automation creates value within the network and self organizing networks are increasingly important not only to lower costs of deployment and operations, but also to offer a better user experience.
Category Archives: LTE Advanced
VoLTE Battery Issue and Solution from ST Ericsson
VoLTE was in bad limelight because of it’s battery performance issues. I wrote an article how VoLTE will consume twice battery than traditional voice calls. The study was done by Metrico Wireless using LG Connect 4G on MetroPCS network.
ST Ericsson provided a new white paper which clarifies all doubts around VoLTE. Without VoLTE CDMA/LTE systems suffer a severe penalty in that they use a concept called Simultaneous Voice and LTE – SVLTE. This means that during a voice call, both the CDMA radio and the LTE radio are in full operation. The consequence of this is clearly visible in the Metrico data, which also shows the obvious fact that VoLTE+LTE consume less power than CDMA+LTE.
But LTE Networks with 3GPP based legacy systems like UMTS and GSM does not suffer from these issue. Also CDMA + LTE solutions based on fall-back schemes do not have this problem.
ST Ericsson provided many way to tackle this issue using better software architecture, optimizing radio hardware and transmission protocols.
What do you think about these solutions? Will these really help in solving battery issue in VoLTE?
Here is the the ST Ericsson white paper on VoLTE battery problem and solution for the problem.
Carrier Aggregation in LTE Advanced
What is carrier aggregation and how this will help in improving bandwidth and throughput?
ITU set specific requirements for IMT Advanced compliant technology should fulfill. Some of these requirements include at least 40 MHz bandwidth, peak spectral efficiency of 15 bit/s/Hz in downlink and 6.75 bit/s/Hz in uplink and control plane and user plane latency of less than 100 and 10 ms respectively. Carrier aggregation is supported for both FDD and TDD.
Carrier aggregation is a LTE Advanced feature to increase aggregate bandwidth in order to improve data throughput in 4G mobile communication systems. Carrier aggregation in LTE was first introduced in 3GPP release 10 and further improvements are ongoing in Release 11 and onward. To make carrier aggregation backward compatible carriers used in this new feature are R8/R9 carriers.
- A Rel-10 UE with reception and/or transmission capabilities for CA can simultaneously receive and/or transmit on multiple Component Carriers (CCs) corresponding to multiple serving cells.
- A Rel-8/9 UE can receive on a single Component Carrier and transmit on a single Component Carrier corresponding to one serving cell only.
Carrier Aggregation is supported for both contiguous and non-contiguous Component Carriers with each Component Carrier limited to a maximum of 110 Resource Blocks in the frequency domain using the Rel-8/9 numerology.
- The number of DL Component Carriers that can be configured depends on the DL aggregation capability of the UE.
- The number of UL Component Carriers that can be configured depends on the UL aggregation capability of the UE.
- It is not possible to configure a UE with more UL Component Carriers than DL Component Carriers.
- In typical TDD deployments, the number of Component Carriers and the bandwidth of each Component Carrier in UL and DL is the same.
The spacing between centre frequencies of contiguously aggregated CCs shall be a multiple of 300 kHz. This is in order to be compatible with the 100 kHz frequency raster of Rel-8/9 and at the same time preserve orthogonality of the subcarriers with 15 kHz spacing.
Carrier Aggregation in Layer 2
In case of Carrier Aggregation the multi-carrier nature of the physical layer is only exposed to the MAC layer for which one HARQ entity is required per serving cell.
In both uplink and downlink, there is one independent hybrid-ARQ entity per serving cell and one transport block is generated per TTI per serving cell in the absence of spatial multiplexing. Each transport block and its potential HARQ retransmissions are mapped to a single serving cell.
The reception timing difference at the physical layer of DL assignments and UL grants for the same TTI but from different serving cells (e.g. depending on number of control symbols, propagation and deployment scenario) does not affect MAC operation. A UE should cope with a relative propagation delay difference up to 30 microseconds among the component carriers to be aggregated in inter-band non-contiguous CA. This implies that a UE should cope with a delay spread of up to 31.3 micro seconds among the component carriers monitored at the receiver, since the BS time alignment is specified to be up to 1.3 microseconds.
Layer 2 Structure for downlink with CA configured
Layer 2 Structure for uplink with CA configured
RRC Carrier Aggregation
When CA is configured, the UE only has one RRC connection with the network. At RRC connection establishment/reestablishment/handover, one serving cell provides the NAS mobility information (e.g. TAI), and at RRC connection reestablishment/handover, one serving cell provides the security input. This cell is referred to as the Primary Cell (PCell).
In the downlink, the carrier corresponding to the PCell is the Downlink Primary Component Carrier (DL PCC) while in the uplink it is the Uplink Primary Component Carrier (UL PCC).
Depending on UE capabilities, Secondary Cells (SCells) can be configured to form together with the PCell a set of serving cells. In the downlink, the carrier corresponding to an SCell is a Downlink Secondary Component Carrier (DL SCC) while in the uplink it is an Uplink Secondary Component Carrier (UL SCC).
Voice Over LTE – VoLTE is Battery Killer
Voice Over LTE – VoLTE is the technology which will drive the future of voice call over next generation mobile networks and it will replace legacy circuit switched call technology. But recent studies made by Metrico Wireless give some scary results for mass implementation of VoLTE. The worst part is that VoLTE calls consumes more than twice battery power than traditional CS calls.
Every year smartphone battery is getting bigger and bigger. Some of the latest smartphones have the most powerful battery compared to last generation smartphones and it’s increasing at a rate of 14% per year. But still these larger batteries are not enough. The average device now has a dual-core processor, as many as five radios, a high-resolution display, one or more HD cameras, and multi-tasking apps, providing sophisticated new functions for subscribers—while increasing battery drain.
Metrico Wireless conducted studies in two different US cities comparing power consumption due to VoLTE on LTE network and they compared the results with same carrier’s CDMA network. Though Metrico Wireless did not mention the name of the operator, it is easy to guess as there is only one operator supports VoLTE in US.
MetroPCS is the only U.S. operator with a live VoLTE service and a commercially available handset. The 1540 milliamp hour (mAh)-battery on Metro’s sole VoLTE handset, the LG Connect 4G, also lines up with the battery capacity of the device Spirent tested.
The test was conducted for 10 minutes and average power consumption od 10 minute CS call over CDMA was 680 milliwatts (mW) and in the same time 10 minutes VoLTE call over LTE network consumed 1358 mW. Spirent estimated that on a full charge, its test smartphone could support 502.6 minutes of talk time using CDMA only, but the same charge would only deliver 251.8 minutes of talk time using VoIP on the 4G network. And that’s with all other data communications turned off.
If this proves to be typical for VoLTE handsets, it will be a big problem. The battery life of the first generation of LTE smartphones was atrocious, and handset vendors have tried to address the problem by slapping fat 3000+ mAh power cells onto their phones. Some carriers are already reluctant to embrace VoLTE since they can still squeeze plenty of life out of their 2G and 3G voice services. If VoLTE proves to be a battery killer, they will be even less inclined to move mobile voice into the IP age.
There are some good news about VoLTE though. Metrico Wireless found that for Multi-RAB scenarios when both Data and VoLTE are active at the same time, LTE performed better than CDMA but with a small margin.
The conclusion is that a lot need to be improved in VoLTE in terms of power consumption.
LTE Circuit Switched Fallback (CSFB) Performance
LTE was developed for packet based services. But a majority part of today’s traffic comes from CS based services like Voice and SMS. So 3GPP agreed to provide an intermediate solution for CS (Circuit Swtich) based services till IP based services like VoLTE completely developed and deployed. Using CSFB (CS Fallback) UE can move to GERAN, UTRAN or CDMA2000 systems for voice services. CS fall back services are available in those areas where EUTRA systems overlap with GERAN, UTRAN or CDMA2000.
CS Fallback (CSFB) will be the bridging technology to ensure that LTE smartphone users can enjoy ultra-fast data services as well as high-quality voice services on 2G/3G networks. CSFB will enable devices in packet-switched LTE networks to change over to CS networks for incoming and outgoing voice calls. In many cases, CSFB will co-exist with Voice over Long Term Evolution (VoLTE) well into the future. Going forward, IMS-based Voice over LTE (VoLTE) will be the logical choice to provide voice services over the same technology that is driving the data revolution. There are compelling reasons, however, to provide CS-based voice services for LTE smartphone users, even in markets were LTE networks have been commercially launched. The Next Generation Mobile Networks Alliance (NGMN) has recommended standards-based CSFB to enable non-IMS roaming subscribers to use both LTE data services and voice services in Circuit Switched (CS) networks. With CSFB, when an LTE smartphone makes or receives a voice call, it connects automatically to the 2G/3G network. T he ongoing LTE data session is also transferred to the 2G/3G network. Once the call is terminated, the smartphone reverts to the LTE network. This process is seamless to the end-user.
CSFB provides LTE voice capability without requiring significant changes in the existing mobile CS core network, for example in routing or charging configurations. The interface between the CS network and the Evolved Packet Core (EPC), which controls the LTE connection, is the cornerstone of CSFB. The standard SGs interface enables CSFB between these two networks.
LTE Circuit Switched Fallback (CSFB) Architecture
CSFB Performance Summary
Qualcomm had done some performance evaluation of different CS Fallback methods. Here are the results of this.
- Device is registered for both CS and PS services via LTE
- CS voice pages are delivered over LTE
- Device remains on LTE except for voice calls
- SMS can be received over LTE
- For voice calls, UE falls back to UMTS/GSM/C2K
- Mobility methods supported
Different CS Fallback Options
| Method | Target Info | Target Prepared | Measurements | LTE → W | LTE → G | LTE → C2K |
|---|---|---|---|---|---|---|
| Redirection | Target Frequency | No | Optional | Yes | Yes | Yes |
| Cell Change Order | Target Cell | No | Required | No | Yes | No |
| Handover-Based | Target Cell | Yes | Required | Yes | Yes | Yes |
CSFB to UTRAN Call Setup Delay (Mobile-Originated)
Redirection-Based CSFB Call Setup Delay with SI Tunneling Is Comparable to Legacy Call Setup Delay
CSFB to UTRAN Call Setup Delay (Mobile-Terminated)
Redirection-Based CSFB Call Setup Delay with SI Tunneling Is Comparable to Legacy Call Setup Delay
CSFB PS Data Interruption
The Handover Option Provides the Lowest Data Interruption Time; For the Redirection Options, ISR Can Significantly Reduce Data Interruption Time
CSFB to GERAN Call Setup Delay (Mobile-Originated)
RRC Release with SI Tunneling Provides the Best CSFB Solution
1xCSFB Call Setup Delay
e1xCSFB Offers the Shortest Call Setup Time
Conclusion
- CSFB offers a solution with the cost, size, and battery life advantages of single-radio solutions, LTE data speeds, and reliability/ubiquity of 2G/3G voice
- Redirection-based CSFB using Release 9 SI Tunneling, for both 3G and 2G offer call delays within subseconds of legacy call setup delay
- Redirection-based CSFB offers call reliability on par with legacy call setup reliability Compared to dual radio solution, e1xCSFB offers more cost effective device solution and also with shorter call setup delay
Voice over LTE (VoLTE) Overview
Voice Over LTE is the next generation voice and video communication over LTE network.
The mobile communication standard Long-Term Evolution (LTE) is optimized for data transfer and designed as a packet switched all-IP system only; it does not include any circuit switched domain currently used for regular voice and SMS services. Demand for mobile broadband services is proven in the increase of data traffic.
Recently, operators have been launching high-speed data networks with LTE technology. However, voice and SMS business still generates around 70% of total operator revenues globally and it has become clear that voice functionality needs to be provided on LTE networks.
With voice over LTE (GSMA VoLTE IR.92 specification, based on global 3GPP standards) as a basis, consumers will be able to use telecom grade voice, video calling and other new richer communication services on LTE smartphones.
How VoLTE Works
In order for voice to run over an LTE network, an IMS (IP Multimedia System) core network needs to provide the telephony service over IP. MMTel (Multi Media Telephony, deployed on the IMS core) is the solution that provides the telephony service (and presence, video calling, chat, etc.) in both LTE and fixed networks. The LTE radio access network and the Evolved Packet Core (EPC) also need to support VoLTE, which can be achieved by software upgrades.
Operators can use the same core network infrastructure (IMS) for VoLTE as for evolved enterprise and consumer services (mobile and fixed convergence over any access).
Consumers will be able to use operator-provided HD voice, video calling and other communication services (chat, presence, and more) on LTE smartphones and other devices. These services use a regular mobile phone number (MSISDN, Mobile Subscriber Integrated Services Digital Network-Number), and VoLTE brings the operator telephony values into an all-IP mobile broadband network: global interoperability, Quality of Service, roaming and seamless mobility, between any mobile devices, over any access. With VoLTE, both voice and LTE data services can be used simultaneously on LTE smartphones.
References
Way To 1000X Data Rate In Mobile Communication
Mobile data rate is never at its peak in the history and it won’t be sufficient anytime soon in near future. GPRS, EDGE, 3G, HSDPA, HSPA+, LTE or LTE-Advanced none of these technology will ever will make the data hungry mobile devices happy. Why because it’s a never-ending story.
I was watching a football world cup qualifier match two days ago at Malmo stadium between Sweden and Kazakhstan and trying to update my status on Facebook. This was the most horrible experience I have with mobile communication till now. Till the end of the game I could not access network. I was using my Samsung Galaxy S III which is a HSPA+ (42 Mbps) modem inside but that was not enough to get some basic data connectivity.
Yesterday evening I got this awesome white paper from Qualcomm called “1000X Mobile Data Challenge”. The presentation is all about making the present and future wireless network more efficient to get best throughput. Here is a small excerpt from the whole presentation.
The main areas where wireless infrastructure can be improved is broadly divided into:
- More spectrum
- More small cells
- More indoor cells.
More Spectrum
Analysts predict that the mobile broadband traffic will double every year. According to a ITU study Europe will need 1.7 GHz of spectrum by 2020, which is double the amount currently allocated.
Spectrum is a rare resource and the only way to use it is getting the best out of it. All the underutilized spectrum should be used efficiently.
New policies like ASA (Authorized Shared Access) can help to use unused spectrum. ASA takes advantage of the Cognitive Radio techniques that were originally developed for the unlicensed TV White Space and uses them to facilitate sharing in a given spectrum band by multiple licensed networks
Because the spectrum is licensed, ASA licensees can ensure spectrum access and they can allocate capital to build network infrastructure
- Since ASA spectrum is licensed, it becomes possible for the ASA network to provide predictable quality of service (QoS)
- 3G/4G Mobile Broadband Networks Using ASA: macro cells, pico cells, femto cells
- Support for FDD and TDD
- Support for Carrier Aggregation
- Additional carrier can utilize ASA spectrum to provide increased capacity
- ASA Macros can be deployed in key cities where additional citywide capacity is needed
- Pico cells can be deployed at key areas where additional capacity is needed Current Pico cells use traditional licensed spectrum. New ASA Pico cells can provide additional capacity using ASA spectrum in addition to traditional licensed spectrum
More Small Cells and Indoor Cells
Small cells like macro, pico, femto will definitely going to open up any new opportunities in the future.
Macro : Conventional base stations that use dedicated backhaul and open to public access. Typical transmit power ~43 dBm; antenna gain ~12-15 dBi.
Pico: Low power base stations that use dedicated backhaul connections and open to public access. Typical transmit power range from ~ 23 dBm-30 dBm, 0-5 dBi antenna gain;
Femto: Consumer-deployable base stations that utilize consumer’s broadband connection as backhaul; femto base stations may have restricted association. Typical transmit power < 23dBm.
Relays–base stations using the same spectrum as backhaul and access. Similar power as Pico’s.
Heterogeneous Network: A deployment that supports macros, picos, femtos and relays in the same spectrum. HetNet is a big way to reduce load from big cells but the biggest disadvantage is interference. With better interference management HetNet will definitely help.
Will these steps help me update my Facebook status next time?