How Programmatic DOOH Demand Is Structured
The programmatic DOOH supply chain differs from web display in one fundamental way: the screen is the publisher, but the screen cannot run JavaScript. This means the OpenRTB auction must be mediated by a server-side component — the DOOH operator's ad server — that acts as the exchange between incoming creative requests and outgoing VAST responses. There is no header bidding in DOOH; the waterfall is sequential, not parallel.
The Trillboards network implements a server-side waterfall with SSP partners ranked by expected CPM yield for each venue type and time slot. Each position in the waterfall is given a configurable bid timeout (defaulting to 800ms); if no bid is received within that window, the request passes to the next position. The total waterfall can include multiple sequential passes before a fill is secured or the slot goes unfilled.
Integration Depth — What It Means in Practice
Integration depth refers to the number of active DSP connections — buyers who have both technically integrated with the SSP and are actively submitting bids on at least a weekly basis. A technically integrated DSP that has paused all DOOH spend does not contribute to fill rate and is not counted in the active integration figure.
Integration depth varies materially by venue category. Fitness and QSR venues have the deepest active integration — the highest number of DSPs submitting regular bids — because these categories have the clearest IAB audience taxonomy mapping and the most established programmatic DOOH budget allocations. Transit and education venues have the shallowest active integration, consistent with the CPM benchmarks in Chapter 4: lower CPM ceilings attract less DSP attention.
Private Marketplace Architecture
Private marketplace (PMP) deals now account for approximately 34% of total bid volume in the network, up from an estimated 22% in 2025. PMP growth is concentrated in the healthcare, fitness, and QSR categories — the same categories that show the highest CPM benchmarks in Chapter 4. This correlation is not coincidental: PMP deals establish floor prices and guaranteed impression volumes that enable DSPs to model DOOH into their programmatic workflows with predictable delivery guarantees. Open exchange DOOH, without these guarantees, is harder to model and attract repeat spend against.
The structure of PMP deals in DOOH differs from web display in two ways. First, DOOH PMP deals are typically time-slot-specific (morning drive, lunch, evening) rather than audience-specific, because time-of-day is the most reliable predictor of venue audience composition in contexts without real-time sensing. Second, deal IDs in DOOH are generally venue-type-level rather than site-level — a single deal ID may cover all fitness venues in a market, rather than a specific gym location.
Supply Path Optimization in DOOH
Supply path optimization (SPO) — the DSP practice of preferring specific supply paths to reduce auction duplication and fee layers — is arriving in DOOH ahead of most industry expectations. DSPs that have completed DOOH-specific SPO audits in 2025 report that DOOH supply chains have fewer intermediary fee layers than web display (typically 1–2 SSP hops versus 3–5 in web) and that the value of SPO in DOOH is primarily about ensuring the deal ID hierarchy is correctly resolved, not eliminating fee gouging.
The practical outcome for operators: buyers who have completed SPO in their DOOH supply path show better bid rates and lower bid timeouts than buyers routing through default SSP configurations. The 12% of bids in the <100ms latency bucket in the table above represents largely pre-bid and cached-deal traffic that has completed SPO.
Fill Redundancy — Why Multiple SSPs Matter
Fill redundancy is the network resilience metric: if SSP position 1 returns no bid, does position 2 fill? The network data shows that in 63% of no-bid outcomes from the primary SSP position, the secondary position delivers a fill. This waterfall redundancy is the structural explanation for why the overall bid_received rate (61%, from Chapter 2) is materially higher than the bid rate from any single SSP partner in isolation.
The economic implication: an operator running a single SSP sees a materially lower effective fill rate than an operator running three or more sequential SSPs with appropriate floor pricing. The setup cost of multi-SSP integration is one-time; the revenue benefit compounds continuously.
Bid Latency — The Hidden Fill-Rate Variable
The 5% bid timeout rate in the latency distribution represents requests where the DSP technically had a matching bid but failed to respond within the timeout window. From a revenue perspective, a timeout is indistinguishable from a no-bid — the slot goes unfilled. The distinction matters for optimization: a no-bid means the DSP had no interest; a timeout means the DSP had interest but couldn't respond fast enough.
Timeout concentration is highest in two contexts: international routes (where bid requests must traverse additional network hops to reach DSP endpoints that are US-datacenter-primary) and complex targeting requests (where the DSP must resolve multiple audience segment lookups before returning a bid price). Both are addressable through infrastructure choices — regional ad server deployment for international markets, and pre-cached audience segment resolution for high-complexity requests.
What Changed Since 2025
The most significant structural change in the demand ecosystem is the emergence of DOOH-specific DSP seats — dedicated buying workflows optimized for DOOH rather than the "DOOH check box" that existed in most DSPs through 2024. DOOH-specific seats understand venue taxonomy, time-slot targeting, and proof-of-play reporting in a way that the generic programmatic seat does not. Their arrival has improved bid quality (fewer bids that technically clear the floor but fail creative review) and increased average winning bid CPM.
What to Expect in 2027
The sequential waterfall model is under pressure. Two developments may accelerate a transition toward server-side parallel bidding (a DOOH equivalent of header bidding) by 2027: first, VAST 5.0 draft specifications include provisions for parallel SSP evaluation; second, the IAB's OpenRTB 3.0 DOOH profile, if finalized in 2026, would establish the shared protocol layer that parallel bidding requires. The network effect of parallel bidding would be a material improvement in bid_received rates — potentially moving the 61% figure to 75–80% for Tier 1 markets — at the cost of increased server-side compute per request.
Implications for Advertisers
The demand ecosystem architecture — sequential waterfall, SSP-mediated, PMP-forward — means that DOOH buying requires a different workflow than web programmatic. Buyers should activate deal IDs before launching campaigns (not after), verify timeout configuration with their DSP team for DOOH-specific endpoints, and use proof-of-play reporting to validate that bid-won impressions translated to actual plays. The gap between bid-won and play_completed in Chapter 2 (render_started to play_completed) is the accountability metric that distinguishes DOOH from other programmatic channels.
Implications for Venue Owners
The economic case for multi-SSP architecture is clear in the data: fill redundancy from a second SSP fills 63% of primary no-bids. Venue owners operating through a single SSP should discuss multi-SSP waterfall configuration with their network operator. The setup complexity is borne by the operator, not the venue; the revenue benefit is shared proportionally.
External References
- IAB Tech Lab (2025). OpenRTB 2.6 — DOOH Extensions. Interactive Advertising Bureau Technology Laboratory.
- IAB (2025). Supply Path Optimization: DOOH Guidance Note. Interactive Advertising Bureau.
- eMarketer (2025). DOOH Programmatic Infrastructure: SSP and DSP Landscape. Insider Intelligence.
- OAAA (2025). Programmatic DOOH Ecosystem Map. Outdoor Advertising Association of America.