Samsung Electronics Co., Ltd & Anor v ZTE Corporation & Ors

A patent claim for a wireless-communications system is not obvious merely because each step in a proposed development could be taken. The court must ask whether the skilled person would take the route for a technical reason, without hindsight, and must stand back from a step-by-step analysis. A claim is not a collocation where its features operate through one signal whose functions are materially linked; claim terms must be construed consistently. A challenge based on lack of technical contribution must address the claim as a whole unless a true collocation has been established. The claimed arrangement for signalling an SSB index through an interleaved demodulation reference signal was therefore valid.

Samsung sought declarations concerning the validity, essentiality and infringement of EP(UK) 3,934,154, a patent concerning synchronisation-signal blocks in 5G initial access. ZTE accepted essentiality and infringement absent a licence but counterclaimed for revocation. This technical trial concerned claim 1 only; the other claims stood or fell with it.

ZTE relied principally on the February 2017 RAN1 technical document LG 434, alleging obviousness. It alternatively alleged that the claim was a collocation of an IFDM and wider-bandwidth arrangement and an SSB-index feature, relying on LG 438 for the former and LG 434 for the latter. It also alleged lack of technical contribution or plausibility. The central issues were the skilled person and common general knowledge, inventive step, interaction between the claim features, and technical contribution.

Disposition. The patent was held valid, essential to 5G and infringed by ZTE. The court declared it valid, essential and infringed, noting that infringement threatened to continue in the absence of a FRAND licence.

1. Skilled person and common general knowledge. The court applied the established-field approach in Illumina Cambridge v Latvia MGI Tech [2021] EWHC 57 (Pat) and Alcon v Actavis [2021] EWHC 1026 (Pat). The problem addressed by the patent arose specifically in NR cell search and initial access. The skilled person therefore operated within the emerging 5G and 3GPP context. Relevant RAN1 agreements and working assumptions formed part of the skilled person’s common general knowledge. The court also upheld an objection to new technical material raised only in late cross-examination, applying Merck KGaA v Merck Sharp & Dohme and others [2025] EWHC 2376 (Ch).
2. Inventive step. The statutory question under Patents Act 1977 remained decisive. Structured approaches were tools only. Prior art had to be assessed without hindsight, and a step-by-step journey had to be tested by asking whether the skilled person would take each step for a technical reason. Although LG 434’s proposal 2 was a good idea worth considering, ZTE did not establish that the skilled person would proceed to the claimed combination. The proposed IFDM arrangement was not convincingly justified. The wider-bandwidth reasoning was technically flawed and inconsistent with the earlier analysis. The claim was not obvious over LG 434.
3. Collocation. Applying SABAF SpA v MFI Furniture Centres Ltd [2004] UKHL 45 and related authorities, the court asked whether the claim concerned one invention or independent inventions. The DMRS had to be construed consistently throughout the claim. It both demodulated the PBCH and carried sequences indicating the SSB index. Integer 1D therefore affected the meaning and operation of integer 1C. The claim was an overall system, not a mere collocation, and the collocation attack failed.
4. Technical contribution. The court rejected an integer-by-integer lack-of-contribution analysis. In the absence of a successful collocation case, the claim had to be considered as a whole. The accepted essentiality of claim 1 to the 5G standard reinforced the conclusion that it made a technical contribution. The technical-contribution and plausibility attack failed.

This was a first-instance technical validity trial. The judgment records an earlier FRAND trial in the same proceedings, decided at [2026] EWHC 999 (Pat) , but no appeal was described.