VMO2 AI-RAN Trial Used Custom Silicon, Not GPUs

Light Reading reported on 2 November that Virgin Media O2's AI-RAN trial at Paddington, central London, did not use an Nvidia GPU. Nokia told the publication that the site ran its AI-RAN software on existing Marvell custom silicon, a Layer 1 chip Nokia calls ABIP, and Light Reading withdrew its original story. My post VMO2 Finds AI-RAN Does Not Need GPUs said the trial ran on a GPU, following that original report, and that detail was wrong, it has been corrected since. The result VMO2 described is unchanged: AI-based channel quality estimation raised spectral efficiency by 20%, and he said a GPU is not required to do it.

Nokia relies exclusively on Marvell silicon for Layer 1 in its RAN products today, and ABIP is the last custom chip it plans to develop. Its successor, ABIG, is built on Nvidia technology. The 20% at Paddington equals the figure Nokia gave in the summer for AI-RAN on GPUs, when it projected 50% in 2027 and a doubling by 2028. A white paper from Chetan Sharma Consulting that Nokia endorsed was more cautious, noting that a site already close to its theoretical spectral efficiency has less headroom for AI gains. Neither the Paddington result nor the GPU figures come with a baseline.

This is the position I took in Ericsson and Nokia at odds on AI-RAN silicon and in Is AI-RAN the future of telco?: using AI in the RAN and buying GPUs are separate decisions. The evidence now covers both vendors. Ericsson reports about 10% from an AI successor to link adaptation on about 60,000 deployed base stations, and Nokia's trial reached 20% on installed silicon. Nokia's argument for GPUs is that they receive years of software upgrades while custom silicon is replaced more often. That is the case to be tested, and it depends on how much AI headroom each generation of ASIC has, which neither vendor has published. Operators weighing ABIG against ABIP-class hardware need that figure, together with a baseline and a cost per site, before they commit to the upgrade.

VMO2 Finds AI-RAN Does Not Need GPUs

Virgin Media O2 has trialled AI-based channel quality estimation on a Nokia RAN at a busy site in Paddington, central London. Light Reading reported on 2 November, after withdrawing its earlier story, that the site ran on Nokia's existing Marvell custom silicon and not on an Nvidia GPU. Rob Joyce, VMO2's director of mobile access engineering, said the AI raised spectral efficiency by 20%. He also said a GPU is not required to do this and described Ericsson's silicon as very good. Ericsson CEO Per Narvinger has said about 60,000 base stations operated by its customers already run an AI successor to link adaptation on existing ASICs, with a gain of around 10%.

VMO2 has no GPU RAN in the £700 million tranche of network spending announced earlier this year, and Joyce favours a distributed RAN. Centralising GPU baseband would require CPRI or eCPRI links of 25 Gbit/s each, about 3 of them or 75 Gbit/s, to a site that has 10 Gbit/s of fibre today. In his words, a distributed deployment means putting additional baseband GPU resources at each site, which is the cost that has to be weighed against the gain.

The 20% and the 10% cannot be compared. They come from different vendors, different algorithms and different scales: 1 trial site against a deployed base of 60,000. Light Reading's report gives no baseline, test duration or site count for the 20%. I made the case in Ericsson and Nokia at odds on AI-RAN silicon that the decision to use AI in the RAN is separate from the decision to buy GPUs, and VMO2's engineering lead now says the same. That keeps the position from Is AI-RAN the future of telco? intact: the commercial case for GPU RAN depends on benefits beyond radio algorithms that ASICs can also run, and no operator has published a baseline or a cost per site to show it. For Nokia customers the choice is narrower than the technology case suggests, because Nokia's last custom silicon product is the one VMO2 trialled and its roadmap runs through GPUs.