re: Upgrading from TDMA/cdmaOne to cdma2000
<< so whose handsets are they going to use I wonder? >>
So who said there would be handsets? <g>
Probably Motorola. Maybe Samsung that keeps slipping dates. Others pretty scarce.
[Undated Article]
>> Upgrading from TDMA/cdmaOne to cdma2000
cellular.co.za
From the operator perspective, there is relatively little effort involved in upgrading a cdmaOne network to 1X. In all, a 1X upgrade does not require any hardware "forklifting", just some tweaking. They will be able to use most of their existing infrastructure to allow backwards compatibility to IS-95 users.
To reach the panacea and slew of advanced multimedia services that a 1X implementation promises, cdmaOne operators will have to do some retrofitting of base station and base channel cards with 1X cards, implement software upgrades in specific areas of their existing networks, and add are some new IP-centric boxes to allow them to implement the data/voice 1X specification in part or in full. The approaches will differ in form depending on what vedor equipment has been chosen, although most vendor approaches include ensuring backward compatibility with existing base stations, with flexible future-proofing hooks for new technologies like intelligent antennas to boost capacity.
What stays relatively intact in a 1X overlay of a cdmaOne network is the MSC (Mobile Switching Centre), antenna systems, amplifiers, filters, and the existing data core of IS-95 networks called the IWF (Inter Working Function). The IWF interfaces to the MSC via a Lambda switch and allows cdmaOne terminals access to a relatively limited packet data offering of around 9.6kbps. It is retained in a cdmaOne upgrade to 1X to provide this backward data compatibility. The MSC requires a software upgrade.
At the Base station level, new channel cards are required to support the increased capacity and enhancement in IP provisioning. New radio control software will also be required in the BS to enable the new channels, and where appropriate, software upgrades will also be necessary for Base Station Controllers. Some operators may however want to implement separate boxes in the BSs in parallel with existing cdmaOne cards, primarily for cdmaOne backwards compatibility, and 1X testing imperatives.
The new software in the BSs and BSCs embody Coherent Reverse Link, additional Walsh code structures for more channels and capacity, a new Power Control scheme as well as a new padding and Synchronization Channel Messaging to allow users to speed up access to new data facilities.
When necessary, 1X upgrades will also support supplemental channel structures if voice and data are in the same channel and there is a need to increase capacity of either at a given time and circumstance.
To complete the new 1X data/voice symphony, operators will also have to add additional hardware to define a new, comprehensive high-speed IP-centric environment lacking in cdmaOne networks. Most of the new IP hardware in 1X systems is, unlike the GPRS world, off-the-shelf and does not need to be specifically designed or modified to exist in the wireless universe. This ensures investment protection.
These new components - which will exist in parallel with the IWF - include the PCF (Packet Control Function) to act as an interface to the MSC and to the PDSN (Packet data Service Node), another new 1X addition. The PDSN is a wireless-savvy router that acts as an interface to the Internet and Intranets.
Another new addition is the AAA (Accounting, Authentication and Authorization) node which hangs off the PDSN to provide service profiles of end-user specific data for packet data operations. The PCF was designed to allow the AAA and PDSN to be as off-the-shelf as possible as to ensure interoperability, and to allow a smooth transition to 3G services.
In later iterations of cdma2000, so-called "soft switches " will allow cdmaOne networks with 1X overlays to carry their voice calls over IP in the backhaul, rather than the current methodology that use CSD.
TDMA networks wanting to overlay 1X will require inter alia new Hybrid Base Stations, new dual mode TDMA/1X terminals for users, a new PDSN, new BSC software, and new MSC software along with all the other components that make up a 1X network.
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Although the 1X upgrade and later 1X-EV-DO (Data Only) iterations do not specifically require any increase in base station numbers, because of the increased fidelity required to maintain promised QoS speeds and low latency for multimedia applications, more BS and BSCs may in fact be necessary at the edge of the networks where Signal To Noise (S/N) ratios impact on data rates.
The necessity for improved amplifier and antenna systems to produce the required fidelity might also arise in some circumstances, although 1X promises an up to 35% improvement in coverage using existing base stations, filters, amplifiers, and topography. It is anticipated that operators in densely populated areas will want to get the full benefit of 1X by upgrading to 1XEV where data demand is high.
Operators will also have to address voice capacity issues with other technologies like Smart Antennas and Dynamic Power Control. The increase in RF capacity with 1X enables more simultaneous users, which means increase in Revenue per Cell Site and higher Return on Investments, but also means that operators will need to mediate between simultaneous higher demand for voice and data.
Operators will have the flexibility to support this growing demand for voice and data without allocating bandwidth specifically for data before customer demand requires it. Some vendors allow operators to protect their voice revenues by dedicating capacity to voice, which is given the highest priority. This could also encompass throttling data rates up and down for users according to demand and specific business models. The overlay design of 1X and its spectral efficiency protects valuable voice revenue, as the provision of medium and high rate IP-based services will not necessarily impact on voice capacity.
Peak, symmetrical data rates of 153.6kbps in ideal conditions are possible, but field trails suggest that as this is a shared resource, 130kbps average aggregate throughput is more likely. This will be shared by many users, which could decrease available bandwidth to individual users, much like heavy usage on an office LAN chocks individual demand. However, since usage scenarios suggest the likelihood of more bursty-type "surfing" where all of the available bandwidth is not swallowed up in one gulp by a few users, fairly high throughputs nearing the 130kbps are possible for individual users.
The new AAA nodes will also be busy collecting varied types of billing information, as operators devise new methods of billing for the slew of new services anticipated to come on stream as a result of the always-on high speed 1X capabilities.
The paradigm will thus change for pure-time based billing to a combination of time and data usage. The billing scenarios may include flat rate models that bundle talk-and-surf, or billing incorporating tiered levels of service with premium billing for QoS assurances for data and voice quality. These include QOS support via Low Delay Tolerance, Data Rate Guarantee, and priority Service Access for Multimedia Applications.
They may also be able to bill for hot spot coverage in convention centers, stadiums, malls and campuses, and for dedicated data rates and coverage to group of users. Operators may also be able to offering premium voice quality to certain users at a premium price using V2 Voice Mode (V1 is a standard voice quality), as well as offering Improved Grade of Service (GoS) and customer satisfaction with service. <<
- Eric - |
