Where is User Experience from the product life cycle process?

In an incremental model like Agile, the User Experience team should be present throughout the whole development cycle of all the sprints with impact on the user interface.

In a watrerfall model, the user experience team should be present right after the business requirements are presented, in order for the business area to make the best decision based on all possible development options, since the user experience possibilities will probably impact the project in terms of costs, time and possible beneffits. This shoud be done prior to the technical requirements specification in order for that document to focus on the selected alternative.

Thanks for providing the same question with much more precision.

The process of user experience in product life cycle must be "OUT & IN" model but usually most of the product based companies start with the same and end up with "IN & OUT" model i.e., "IN & OUT" means waterfall model.

They collect data from market through agencies and design the system to evaluate the user experience normally it is due to stringent business policies and skewed and unrealistic dead lines. 

Normally the follow goes like this in IN & OUT model

1. Determine objectives

2. Evaluate alternatives

3. Prototype

4. Validate

5. Final product

We try to integrate user experience into the process.

But this method may take us near to the actual user requirements but difficult to fulfill100% user requirements. 

Instead of this if corporate companies allows us to study the actual user first instead of studying user requirements (perceived) we can launch products which will bring the ultimate bliss of experience to our customers.

In general, post-purchase customers become users as they interact with the product to achieve their goals & tasks in their context of use. But pre-purchase, there is also a period where the user experience (and usability) plays a key role in the end-to-end experience.

There is typically4 stages in an Standard Product Life Cycle:- (User experience or buying behavior is synced in each of these stages) 

1st Introduction:- This is the stage where either an existing company brings in new Brand or range or an new company enter's the existing market. Instance if it's consumer durable's or FMCG products than an typical company focuses on Advertising, Innovative Marketing, BTL (Below The Line or In-Store) activities, Offers & Promotion's etc. From Company point is attracting consumers (Potential) towards their products & making them use it. From the consumer point it's an trial zone. Where some consumers may look forward to try it, check if it relates to them etc (Not all but some would try out)

2nd stage Growth Stage: This stage if "Introduction" was successful & consumers have tested or tried & liked the product. This usually means from the Company point: Consumers have liked the product & they would be able to recognize it. This stage signifies as this is the stage 'Product' actual becomes or involves in the process of becoming an 'Brand' from just a product. Companies may not so much involve in Promotion's (Depending on the level of competition too) but focus would be on brand building measures, ATL activities will be more etc. From the Consumer point of view: It means their initial experience or trial was good, they liked it & are comfortable relating it (It acts as a personality reflection) to the "loyal Consumers'. They would be sure of the quality & benefits of using it (Or even reaped some). They would be easily recognize from the 'Shelves' among others & would be happy recommending Friends & Family about the product.

3rd Stage Maturity Stage: This stage is critical for both the consumer & Company point of view. As this is the period where companies should bring in new variant's, ranges or an updated version or an new taste. This will help companies not generate higher 'Profits' from the existing range with a large percentage of 'Loyal Consumer's' but would be in a better position to leverage the successful brand's Image to the new products. On the Consumer point: This is a period where an consumer is using the same product for a quite a while or a period & starts expecting different variants, upgraded benefits or an change in the representation (Packaging) etc. This period consumer's would be more interested to try any new brand's of the current company they are using than others. 

4th Stage is Decline: If the company fails to acknowledge the Importance of Innovation or 'Change' it will gradually feel it in either Financially or Business wise. If it fails to retain the existing consumers along with attracting new clients or customers. (Hindustan Motor Company is an perfect example for the current situation).

This stage companies usually start loosing Market Share, decrease in sales, decrease in consumer loyalty & if right steps not taken would reach an 'Dead end'.

This stage arises also with the level of Competition, Innovation, Consumer Knowledge & expectations.

From the consumer point of view: They are bored of using the same product for an considerable period of time or there are better products available with better qualities, benefits, increased level of satisfaction etc.

In each stage the company has a change to revive itself. It's an regular updation's or consumer engagement would take the company to the constant growth path.

As consumer or User experience is Psychological based on their perception or expectation's it acts as a sync with each stage of PLC (Product |Life Cycle).

I believe with the above references i had been able to give some references. :-)

UX is a very important part to be added to your product life cycle ,

and where it is in your product cycle that is dependent in a lot of factor like ( Management Approach , development process , development methodologies , ... )

But you have to know that the UX process could have another small circle on it !

So , let us assume that our simple life cycle like following :

• Definition
• Requirements And Research
• Analysis
• Product Development
• Testing
• Delivery

And let us assume that the UX team had another cycle process need to be ready while the Product Development phase like this:

• Solution Concept and problem definition
• Wire-framing
• Prototyping

So you can see the UX team can't start this process until the finish of the analysis phase ib the main life cycle process and before the testing phase on your main  life cycle process.

i hope those words make things more simpler to you .