What is the estimated growth rate of traffic and demand from a wireless standpoint that will determine the number of cell sites needed for site densification 
be our estimation. And you'll see the carriers continue to convert legacy 3G into either 4G or maybe skipping a generation and going directly to 5G. The sites upon which they were previously, we would expect those will be largely repurposed into the next generation of communications infrastructure.
Operator
We'll move to the next question. Next, we'll go to Tim Horan with Oppenheimer.
Tim Horan -- Oppenheimer -- Analyst
Thanks guys. So Jay, do you think ultimately the mid-band spectrum we need like twice as much cell sites as we would given the limitations on physics? And can you talk about what type of ARPU risk you would expect as they upgrade each one of these cell sites? I know there's a million moving parts. The antennas are smaller, that there's MIMO in it, maybe they're deploying C-RAN with it, but just rough idea on both of them. Thank you.
Jay A. Brown -- President And Chief Executive Officer
Yes. Ultimately, the number of sites that will be needed will be a function of what's the growth rate of traffic and demand from a wireless standpoint. I think the table that we put into the presentation is helpful because it shows directionally the move and the need for investment toward site densification. How much site densification ultimately happens I think will be a function of what's the growth rate in data. And under, I think, any scenario that you could come up with, we feel really good about where we're positioned against that growth rate and think that we'll be able to continue to deliver on our long-term target of 7% to 8% per year growth in our dividends per share. On your second question around ARPU, I think I'd defer that to our customers and let them speak to what they see as the revenue opportunity per user as the spectrum bands get deployed and built out.
Tim Horan -- Oppenheimer -- Analyst
Well, I was referring a little bit more how much revenue you could get per cell site for upgrades roughly. I mean the antennas are a lot smaller, and it's much less money than a 600-megahertz upgrade to do a 3.5. Or any thoughts around how much more they have to spend per site?
Jay A. Brown -- President And Chief Executive Officer
Sure, Tim. As they deploy the spectrum, sometimes we'll see on a tower site, based on traffic or usage that -- or need that they have, they'll deploy a full installation. And that may be nine antennas and lines or more. And occasionally, we'll see it more in the form of an amendment where they're swapping out antennas, increasing size of antennas, and it's really a site-by-site decision that the carriers are going to make. So being really specific as to what the opportunity of dollars per site will ultimately be for us is probably more precise than we're able to be. But directionally, in terms of return on assets, both on the tower side and on the small cell side, I think the deployment of these spectrum bands enables us to increase both our revenues and gross margin at the per-site level and then most importantly increase our yield on assets over time as we lease up the assets.
Tim Horan -- Oppenheimer -- Analyst
Thank you.
Jay A. Brown -- President And Chief Executive Officer
Operator, may we can take one more question before wrapping up.
Operator
Next, we'll go to David Guarino with Green Street.
David Guarino -- Green Street -- Analyst
Hey, just a quick one. I just want to follow up. I think it was on a question Spencer had asked. Could you guys give your view on T-Mobile's activity on the small cell leasing side over the next few years? And the reason I asked is just trying to understand the rationale for making a large upfront payment today rather than just amending the contract, assuming that was an option.
Jay A. Brown -- President And Chief Executive Officer
Yes. David, good morning. We really don't like to speak to our customers' deployment plans. Let them -- we want to let them speak for themselves around why they make the decisions that they make around network investment and view. These sites that they canceled were locations where T-Mobile is going to have small cells, and I beli
be our estimation. And you'll see the carriers continue to convert legacy 3G into either 4G or maybe skipping a generation and going directly to 5G. The sites upon which they were previously, we would expect those will be largely repurposed into the next generation of communications infrastructure.
Operator
We'll move to the next question. Next, we'll go to Tim Horan with Oppenheimer.
Tim Horan -- Oppenheimer -- Analyst
Thanks guys. So Jay, do you think ultimately the mid-band spectrum we need like twice as much cell sites as we would given the limitations on physics? And can you talk about what type of ARPU risk you would expect as they upgrade each one of these cell sites? I know there's a million moving parts. The antennas are smaller, that there's MIMO in it, maybe they're deploying C-RAN with it, but just rough idea on both of them. Thank you.
Jay A. Brown -- President And Chief Executive Officer
Yes. Ultimately, the number of sites that will be needed will be a function of what's the growth rate of traffic and demand from a wireless standpoint. I think the table that we put into the presentation is helpful because it shows directionally the move and the need for investment toward site densification. How much site densification ultimately happens I think will be a function of what's the growth rate in data. And under, I think, any scenario that you could come up with, we feel really good about where we're positioned against that growth rate and think that we'll be able to continue to deliver on our long-term target of 7% to 8% per year growth in our dividends per share. On your second question around ARPU, I think I'd defer that to our customers and let them speak to what they see as the revenue opportunity per user as the spectrum bands get deployed and built out.
Tim Horan -- Oppenheimer -- Analyst
Well, I was referring a little bit more how much revenue you could get per cell site for upgrades roughly. I mean the antennas are a lot smaller, and it's much less money than a 600-megahertz upgrade to do a 3.5. Or any thoughts around how much more they have to spend per site?
Jay A. Brown -- President And Chief Executive Officer
 Sure, Tim. As they deploy the spectrum, sometimes we'll see on a tower site, based on traffic or usage that -- or need that they have, they'll deploy a full installation. And that may be nine antennas and lines or more. And occasionally, we'll see it more in the form of an amendment where they're swapping out antennas, increasing size of antennas, and it's really a site-by-site decision that the carriers are going to make. So being really specific as to what the opportunity of dollars per site will ultimately be for us is probably more precise than we're able to be. But directionally, in terms of return on assets, both on the tower side and on the small cell side, I think the deployment of these spectrum bands enables us to increase both our revenues and gross margin at the per-site level and then most importantly increase our yield on assets over time as we lease up the assets.
Tim Horan -- Oppenheimer -- Analyst
Thank you.
Jay A. Brown -- President And Chief Executive Officer
Operator, may we can take one more question before wrapping up.
Operator
Next, we'll go to David Guarino with Green Street.
David Guarino -- Green Street -- Analyst
Hey, just a quick one. I just want to follow up. I think it was on a question Spencer had asked. Could you guys give your view on T-Mobile's activity on the small cell leasing side over the next few years? And the reason I asked is just trying to understand the rationale for making a large upfront payment today rather than just amending the contract, assuming that was an option.
Jay A. Brown -- President And Chief Executive Officer
Yes. David, good morning. We really don't like to speak to our customers' deployment plans. Let them -- we want to let them speak for themselves around why they make the decisions that they make around network investment and view. These sites that they canceled were locations where T-Mobile is going to have small cells, and I beli